Category: Research

‘Hothouse Earth’: New study finds Earth could enter an even hotter new normal

‘Hothouse Earth’: New study finds Earth could enter an even hotter new normal

By Elisa Jiménez Alonso

A new study published in Proceedings of the National Academy of Sciences (PNAS) shows that Earth could enter what the authors call ‘Hothouse Earth’ conditions where the average global climate could stabilise at 4-5°C above pre-industrial temperatures and sea levels could rise 10-60 m higher than today.

Mitigation alone won’t be enough for ‘Stabilized Earth’

The study, which has received wide-spread attention, also shows that keeping global warming within 1.5-2°C – a state the authors call ‘Stabilized Earth’ – may be a more daunting task than previously thought. It would not only require a significant reduction of greenhouse gas emissions but also enhancing or creating new carbon sinks, efforts to actively remove CO2 from the atmosphere, possibly solar radiation management, and adaptation to climate change impacts that are already happening and unavoidable.

“Human emissions of greenhouse gas are not the sole determinant of temperature on Earth. Our study suggests that human-induced global warming of 2°C may trigger other Earth system processes, often called ‘feedbacks’, that can drive further warming – even if we stop emitting greenhouse gases,” says lead author Will Steffen from the Australian National University and Stockholm Resilience Centre.

Health, economies, and political stability at risk

‘Hothouse Earth’ could potentially be uncontrollable and dangerous to most of Earth’s population, especially if the transition happens within only a century or two, which, following current pathways, wouldn’t be unlikely according to the scientists. This in turn would have fatal effects on health, economy, and political stability, but could also make portions of the planet uninhabitable for humans.

The study shows that agricultural production and water supplies are especially vulnerable to severe climate changes, leading to hot/dry or cool/wet extremes. These, obviously, would have severe impacts on society. The authors say “societal declines, collapses, migrations/resettlements, reorganizations, and cultural changes were often associated with severe regional droughts and with the global megadrought at 4.2–3.9 thousand years before present, all occurring within the relative stability of the narrow global Holocene temperature range of approximately ±1 °C.”

A growing need for building climate resilience

As highlighted in the study, even if a ‘Stabilized Earth’ state is achieved, Earth will be warmer than “at any other time in which fully modern humans have existed.” It would also still lead to the activation of some tipping elements and radical shifts in the ecosystems that support human life. The researchers state that current development strategies focused on economy efficiency will not be able to cope with these trends.

Global map of potential tipping cascades. The individual tipping elements are color- coded according to estimated thresholds in global average surface temperature (tipping points). Arrows show the potential interactions among the tipping elements based on expert elicitation that could generate cascades. Note that, although the risk for tipping (loss of) the East Antarctic Ice Sheet is proposed at >5 °C, some marine-based sectors in East Antarctica may be vulnerable at lower temperatures.

The emphasis now should clearly be on strategies that have the potential to transform human systems and make them climate resilient. Speaking in broad terms, the authors point out five characteristics climate resilience strategies should have:

  1. Maintenance of diversity, modularity, and redundancy;
  2. management of connectivity, openness, slow variables, and feedbacks;
  3. understanding social–ecological systems as complex adaptive systems, especially at the level of the Earth System as a whole;
  4. encouraging learning and experimentation; and
  5. broadening of participation and building of trust to promote polycentric governance systems.

Additionally, the authors of the study emphasise that their initial analysis would need to be underpinned by further research and Earth System analysis and modeling studies to address three critical questions:

  1. Is humanity at risk for pushing the system across a planetary threshold and irreversibly down a Hothouse Earth pathway?
  2. What other pathways might be possible in the complex stability landscape of the Earth System, and what risks might they entail?
  3. What planetary stewardship strategies are required to maintain the Earth System in a manageable Stabilized Earth state?

Steffen, W., Rockström, J., Richardson, K., Lenton, T.M., Folke, C., Liverman, D., Summerhayes, C.P., Barnosky, A.D, Cornell, S.E., Crucifix, M., Donges, J.F., Fetzer, I., Lade, S.J., Scheffer, M., Winkelmann, R., and Schellnhuber, H.J. (2018) Trajectories of the Earth System in the Anthropocene. Proceedings of the National Academy of Sciences (USA), DOI: 10.1073/pnas.1810141115

Cover photo by Siddharth Kothari on Unsplash

 

Met Office finds climate concerns for the UK

Met Office finds climate concerns for the UK

The Met Office published its 4th annual State of the UK Climate report this week that gives a summary of the UK weather and climate through the calendar year 2017, alongside the historical context for a number of essential climate variables. It provides an accessible, authoritative and up-to-date assessment of UK climate trends, variations and extremes based on the previous year’s observational datasets. For the first time this report is being published as a special issue of the International Journal of Climatology, which is the Royal Meteorological Society journal of climate science.

Here are some key facts from the report:

  • 2017 was the 5th warmest year over land in a record dating back to 1910.
  • In contrast to summer 2018, UK summers have been notably wetter over the most recent decade, with a 20% increase in rainfall compared to 1961-1990.
  • Above average temperatures from February to June, and also in October, helped position 2017’s high temperature ranking, whilst the second half of the year saw temperatures nearer to average.
  • Nine of the ten warmest years for the UK have occurred since 2002, and the top ten have all occurred since 1990. The Central England Temperature series, which extends back to 1659, shows that the 21st century (since 2001) has so far been warmer than the previous three centuries.
  • For the UK as a whole, rainfall in 2017 was close to average, but with large regional differences. Much of Highland Scotland and lowland England were considerably dry, whilst west Wales, north-west England, and parts of south-west and north-east Scotland saw wetter condition.

Additional facts are available in the infographic published alongside the report:

Photo by Met Office, 2018

Download the full report here: https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.5798


Cover photo by giografiche/Pixabay.
What was hot before 1976? A trip down British weather’s memory lane

What was hot before 1976? A trip down British weather’s memory lane

By Thomas Webb, University of Liverpool

As clouds and the odd shower break the spell of the recent heat wave, it’s a good time to reflect on our fascination with hot and sunny weather in the UK. A lot of comparisons have been made between this year’s heat and 1976, when Abba were in the charts, flares were in fashion and Britain had its hottest summer for 350 years.

Alongside the winters of 1947 and 1962-3, the summer of 1976 is part of Britain’s cultural weather memory, when temperatures reached 32°C or higher for 15 consecutive days and triggered one of the most severe droughts for the past 150 years. The highest recorded June temperature in the UK was set on the 28th that year, when Southampton sweated in 35.6°C – a record which still stands.

The summer of 1976 has become part of a national narrative and a source of shared positive nostalgia, which has been used as a benchmark for comprehending extended periods of hot weather ever since. The retelling of this national weather story in popular culture is important. It shapes individual memories of the event and influences how individuals construct a personal understanding of their local climate (whether they have a personal memory of this event or not) during exceptional weather.

But what came before 1976? What heatwaves – now largely long forgotten – did people use as a benchmark for comparing hot weather conditions?

‘Day hot’ for Victorian farmers

These questions can be investigated through the use of the online and freely accessible TEMPEST database, the product of extensive archival research by scholars from the Universities of Liverpool, Nottingham, Glasgow, and Aberystwyth. TEMPEST contains more than 18,000 records relating to extreme weather events in Britain spanning the past 500 years. Its collection of diary entries, letters, parish registers and newspaper reports provides valuable insights into how people experienced and responded to unusual and extreme weather.

Searching for heatwaves on TEMPEST reveals that extended periods of hot weather weren’t frequent, but were not necessarily uncommon either. People often made comparisons to previous heatwaves in order to contextualise the hot weather conditions around them.

These comparisons were measured in a number of ways, ranging from contrasting record temperatures to anecdotes rooted in memories, interests, locations and occupations. Some of the comparisons were made in relation to agriculture and farming practices – for instance, during the dry and hot summer of 1826, William Herbert from Great Bowden, Leicestershire wrote in his diary:

21st Aug – The drought is so great that Mr Clarke’s beast were obliged to be brought yesterday from Greenholm to Gunsbrook to be watered, that Brook being dry for nearly a mile together, day hot.
22nd Aug – heard old Joseph Charlton say last night that he remembered the dry summer of 1762, he & his mother took 2 cows to Harboro’ Fair and were bid only 20s for the two, his father took a sow & pigs for which we not bid anything … day hot.

For this Leicestershire farming community, the hot and dry spell of 1826 was benchmarked against similar conditions in 1762. Their severity was remembered in personal terms through the impact the weather had on watering and selling livestock.

Britain’s deadly heat waves

The 1826 drought followed the similarly, and often overlooked, hot summer of 1825. According to Orion’s British Almanac, one of several 19th-century collections of extraordinary weather events and predictions, ten men and 16 horses died under the heat during a hot stretch in July.

In a letter from John Thomas Swanick in Derby to G. Symons of London, Swanick observed that temperatures in July 1825 were as high as “the three hot days which occurred on the 12th, 13th and 14th days of July 1808 when so many persons died by the effects of it and taking cold liquids.” The death toll from a heat wave in 1825 could be linked to a deadly hot weather event 17 years earlier, as a means of categorising the severity of weather over time.

Later in the 19th century and into the early 20th century, it becomes apparent that historical “benchmark” heatwaves replaced one another. This was especially the case when historical heatwaves went out of living memory.

In the Baptisms Register for Thorpe Malsor, Northamptonshire, the summer of 1868 was recorded as a “very dry summer – great drought and scarcity of water in many places round … Old people in this village report that 1818 & 1826 were similar years”.

Likewise, a journalist in 1911 reported, in regards to consistent days reaching 80 degrees Fahrenheit (26.67 °C):

So far, in 1911 there have been 35 such days as against 40 in the historic summer of 1868, the only one in the lifetime of people now living which can compare with the present season.

The summer of 1976 has not passed out of living memory, but in 50 years time it may be summer 2018 that we will be looking back on as our benchmark. As these historical examples suggest, these comparisons will not just be made in regards to temperature records, but will also be measured by other connected events that shape personal and collective weather memories of 2018 – such as the 30°C heat in the UK that accompanied England’s victory over Sweden in the World Cup quarter-finals.

Climate change means that we are likely to see more extreme weather of all kinds. As the signature of climate change manifests in our weather, its growing cultural and political importance will frame the ways in which we look back on the heatwave of 2018 and the weather events that follow.

The ConversationIn the effort to contextualise the weather extremes of the future, our best resources are the stories that make up our shared weather memory of the past.


Thomas Webb, Postdoctoral Research Associate, University of Liverpool. This article was originally published on The Conversation. Read the original article.

Cover photo: Molesey Lock on a busy Sunday.
Past warming shows 2°C brink may be close

Past warming shows 2°C brink may be close

By Tim Radford

Once again, past warming warns of the power of climate change. The surprise is that it doesn’t take much warming to raise sea levels six metres.

Even if the world’s nations keep their promise to contain global warming to within 2°C, past warming shows that the Earth will still change visibly – and perhaps sooner than science currently expects.

Sea levels could rise by six metres.  Large tracts of the polar ice caps could collapse. The Sahara could become green. The edges of what are now tropical forests could turn into savannah, to be seared and maintained by regular outbreaks of fire. The northern forests could move 200 km nearer the north pole and, ahead of them, the tundra.

That is what will happen, if the past is a sure guide to the present. A 2°C rise in temperature is the maximum agreed by 195 nations when they met in Paris in 2015, a promise that can be maintained only by reducing carbon dioxide emissions, chiefly by switching rapidly from fossil fuels to renewable sources such as solar and wind power.

Three times in the last 3.5 million years, the planetary thermometer has risen, to up to 2°C higher than those temperatures humans enjoyed for most of the last 2,000 years. And three times the global climate has changed in response.

What is less certain is the rate of change: a six metre rise in sea levels fuelled by the thermal expansion of the oceans and the loss of the world’s glaciers, and the retreat of the Greenland and Antarctic ice caps, could take thousands of years. But once such changes began it would be very difficult to halt or reverse them.

“The carbon budget to avoid 2°C warming may be far smaller than estimated, leaving very little margin of error”

All geology is based on an axiom that the present is the key to the past: landscape around us tells a story of the conditions under which the rocks were formed. It follows that the past should also foretell the possibilities of the future, and researchers from 17 nations report in the journal Nature Geoscience that they looked again at three recent intervals when the world was warmer.

One of these began at the close of the Ice Age, 9000 to 5000 years ago; one between the last two ice ages 129,000 to 116,000 years ago; and one from a warm period known as the mid-Pliocene 3.3 to 3 million years ago. The first two were responses to very subtle but predictable shifts in the planet’s orbit.

But the oldest of these warmings was driven by an increase of carbon dioxide in the atmosphere to between 350 and 450 parts per million. These are levels that match those of today, as a consequence of 200 years of fossil fuel exploitation.

The research raises questions about the completeness of the climate models now used by scientists to predict future change.

Slow to act

As ice retreats and vegetation cover changes, so does the traffic in carbon between living things and the rocks, ocean and atmosphere. And the catch – for climate modellers – is that although the world’s nations promised to act, action so far has been slow. Fossil fuel is still “business as usual”. And this inevitably will play into the calculations in unpredictable ways.

“While climate model predictions seem to be trustworthy when considering relatively small changes over the next decades, it is worrisome that these models likely underestimate climate change under higher emission scenarios, such as a ‘business as usual’ scenario, and especially over longer time scales,” said one of the scientists, Katrin Meissner, of the University of New South Wales, in Australia.

And Hubertus Fischer, of the University of Bern, in Switzerland, who led the study, said: “Observations of past warming periods suggest that a number of amplifying mechanisms, which are poorly represented in climate models, increase long-term warming beyond climate model projections.

“This suggests the carbon budget to avoid 2°C warming may be far smaller than estimated, leaving very little margin of error to meet the Paris targets.”


This article was originally published on Climate News Network and can be accessed here.

 Fischer, Hubertus; Meissner, Katrin J.; Mix, Alan C.; Abram, Nerilie J.; Austermann, Jacqueline; Brovkin, Victor; Capron, Emilie; Colombaroli, Daniele; Daniau, Anne Laure and Dyez, Kelsey A., et al. (2018) In Nature Geoscience. Access the study by clicking here.

Cover photo (public domain): Illustration of a landscape during the Pliocene period. From “Cyclopedia universal history: Embracing the most complete and recent presentation of the subject in two principal parts or divisions of more than six thousand pages” by Ridpath, John Clark, 1840-1900.
‘Global’ warming varies greatly depending where you live

‘Global’ warming varies greatly depending where you live

By Zeke Hausfather

As part of the Paris Agreement on climate change, the international community committed in 2015 to limit rising global temperatures to “well below” 2C by the end of the 21st century and to “pursue efforts to limit the temperature increase even further to 1.5C”.

However, these global temperature targets mask a lot of regional variation that occurs as the Earth warms. For example, land warms faster than oceans, high-latitude areas faster than the tropics, and inland areas faster than coastal regions.

Furthermore, global human population is concentrated in specific regions of the planet.

Here, Carbon Brief analyses how much warming people will actually experience where they live, both today and under future warming scenarios.

The warming experienced by people is typically higher than the global average warming. In a world where warming is limited to “well below” 2C about 14% of the population will still experience warming exceeding 2C. In the worst-case scenario of continued growth in emissions, about 44% of the population experiences warming over 5C – and 7% over 6C – in 2100.

Warming is not globally uniform

Different parts of the world respond in different ways to warming from increasing greenhouse gas concentrations. For example, ocean temperatures increase more slowly than land temperatures because the oceans lose more heat by evaporation and they have a larger heat capacity.

High-latitude regions – far north or south of the equator – warm faster than the global average due to positive feedbacks from the retreat of ice and snow. An increased transfer of heat from the tropics to the poles in a warmer world also enhances warming. This phenomenon of more rapidly warming high latitudes is known as polar amplification.

Both of these effects can be seen over the past century. The figure below shows warming measured between the start of the 20th century (1900 to 1920) and present (1998 to 2018). Grey areas represent regions where insufficient temperature records were available early in the 20th century.

Warming between 1900-1920 and 1998-2018 based on 1 degree latitude/longitude gridded observational temperature data from Berkeley Earth.

Over this period, on average, the world has warmed about 1C. However, land areas have warmed by 1.3C, while oceans have only warmed by around 0.8C. Some parts of the Arctic have warmed by more than 2C, with a few hotspots of even greater warming where cooler sea ice has been replaced by warmer open water.

By the end of the 21st century, climate models project future average global warming between around 1.5C and 5C, depending on greenhouse gas emissions and the sensitivity of the climate to those emissions. These models show both the land warming faster than oceans and polar amplification continuing into the future.

The figure below shows the average warming between 1900-1920 and 2080-2100 experienced across all of the climate models – called CMIP5 models – featured in the Intergovernmental Panel on Climate Change (IPCC) fifth assessment report. It looks at warming across the four different Representative Concentration Pathway (RCP) future emission scenarios. These span a world of rapid reductions in emissions where warming is held well-below 2C – RCP2.6 – to a world where emissions increase rapidly through the 21st century – RCP8.5.

Warming between 1900-1920 and 2080-2100 in the CMIP5 multimodel mean (one member per model) using data obtained from KNMI Climate Explorer.

Population concentrated in specific areas

Global population tends to be concentrated in specific parts of the world. A large portion of the world’s population is located in India, China and southeast Asia, with much of the rest concentrated in large cities. The figure below shows where global population is expected to be located in 2020, according to projections from NASA and Columbia University.

2020 projected population per 1×1 latitude/longitude grid cell (around 100 square kilometers) using data from the Gridded Population of the World version 4 (GPWv4).

As land areas warm faster than oceans, the fact that people live on land means that they will tend to experience faster warming than the global average change. This is somewhat mitigated by the fact that areas of highest population – India, southern China and southeast Asia – generally experience somewhat lower warming in the future than most other land areas. At least, that is according to the average across all the models.

While predicting exactly how the distribution of population will change by the end of the century is difficult, the existing population locations are still likely to be among the heaviest populated in 2100. However, rapid population growth is also expected in Africa, which may be home to up to 40% of the world’s population by 2100.

Warming where people live

Carbon Brief has combined the 2020 population map with climate model projections to estimate how much warming people will experience by the end of the 21st century. This follows similar efforts by Dr Flavio Lehner and Prof Thomas Stocker in a 2015 paper, Dr Luke Harrington and colleagues in 2016, and Prof David Frame and colleagues in 2017.

The figure below shows the percent of the world’s population experiencing different levels of warming, both during the current period – the left-most column – and under the four different RCP future emission scenarios.

Warming experienced by the global population at present day and in different future RCP scenarios. Based on 2020 projected population data from GPWv4 and CMIP5 multimodel mean warming between 1900-1920 and 2080-2100.

Today, nearly all of the global population has experienced warming of at least 0.5C and about 68% has experienced warming of at least 1C. Around 16% of the population lives in areas that have already warmed more than 1.5C (light blue shading).

In future, the warming people experience depends on how much greenhouse gases are emitted. In a low-emission RCP2.6 scenario, where global temperatures stay well below 2C, about 14% of the population will still experience warming exceeding 2C (yellow).

For RCP4.5, nearly the entire global population experiences warming over 2C, with 26% seeing warming over 3C (orange). In RCP6.0, 63% of the population has warming over 3C and 6% over 4C (red). In the high-emission RCP8.5 scenario, most of the human population would experience warming exceeding 4C, with 44% exceeding 5C (maroon) and 7% exceeding 6C (black).

In a “business-as-usual” world, where action to combat climate change is not undertaken, future warming depends on a lot of factors including population growth, economic growth and technological development. Scientists have recently published a new series of “baseline” no-climate-policy scenarios that generally fall between RCP6.0 and RCP8.5.

The effects of future warming will vary greatly. Understanding how much warming people will experience is useful in understanding its impacts. While the global distribution of population may look somewhat different by the end of the century, people will still typically experience higher levels of warming than the global average temperature change.


This article was originally published on Carbon Brief and is shared under a Creative Commons license. Read the original article here.

Cover photo by Mathias Eick EU/ECHO (CC BY-SA 2.0): Flooding in the Philippines.
Unprecedented summer heat in Europe “every other year” under 1.5C of warming

Unprecedented summer heat in Europe “every other year” under 1.5C of warming

By Dr Andrew King and Dr Markus Donat

As summer gets underway in the northern hemisphere, much of Europe has already been basking in temperatures of 30C and beyond.

But while the summer sun sends many flocking to the beach, with it comes the threat of heatwaves and their potentially deadly impacts. Tens of thousands of people across Europe died in heatwaves in 2003 and 2010, for example, while the “Lucifer” heatwave last year fanned forest fires and nearly halved agricultural output in some countries.

With international ambition to limit global temperature rise to “well below” 2C above pre-industrial levels now enshrined in the Paris Agreement, we have examined what impact that warming could have on European summer temperatures.

Our results, published in Nature Climate Change, find that more than 100 million Europeans will typically see summer heat that exceeds anything in the 1950-2017 observed record every other year under 1.5C of warming – or in two of every three years under 2C.

Human influence on European climate

There has been a substantial amount of work showing that recent heatwaves and hot summers in Europe have been strongly influenced by human-caused climate change.

This includes the very first “event attribution” study that made a direct connection between human-caused climate change and Europe’s record hot summer of 2003. As a densely populated continent, recent hot summers and heatwaves have hit Europe with spikes in mortality rates.

Europe is also a particularly good location to study the implications of the Paris Agreement limits because it has among the longest and highest quality climate data in the world. This means we have a better understanding of what past summers in Europe have been like and we can evaluate our climate model simulations with a higher degree of confidence, relative to other regions of the world.

In our study, we looked at the hottest average summer temperatures across Europe since 1950 and found that for most of the continent these occurred in 2003, 2006 or 2010. There are exceptions, of course. For example, in Central England the hottest summer remains 1976.

You can see this in the graphic below, which maps the decade of the hottest summer across Europe. The darker the shading, the more recently the record occurred.

Map showing decade of warmest summer on record (since 1950). The darker shading shows more recent decades. Source: King et al. (2018)

Using the historical record hot summer between 1950 and 2017 in each location in Europe as a benchmark, we then examined the likelihood of a summer exceeding that record in model simulations. We assessed four different scenarios: a world without climate change, the world of today’s climate, a 1.5C warmer world and a 2C warmer world.

Consistent with previous studies, which have examined specific heat events in Europe like those in 2003 and 2010, we found that the likelihood of recording a new hottest summer today is higher than in a world without human-induced climate change.

Similarly, when we extend our analysis to the 1.5C and 2C world simulations, we find a continued increase in the likelihood of historically unprecedented hot summers at individual locations across all of Europe.

The impact on humans

Our next step was to estimate how many people would be exposed to historically unprecedented summer average temperatures in each of our four model worlds. For this analysis we kept population levels the same (at the 2010 level), rather than factoring in historical changes or future forecasts.

We found systematic increases in the number of people in Europe projected to experience unprecedented summer heat.

In a typical summer in the current climate, we would expect that 45 million Europeans would experience summer temperatures above the existing record for their location. However, in an average summer in a 1.5C world, we project that 90 million Europeans – about 11% of the continent’s population – would experience a summer warmer than any in recorded history. In a 2C world this figure would almost double again to 163 million Europeans (20% of the population).

We also find that the possibility of very high population exposure to historically unprecedented hot summers increases dramatically from the world of today to a 1.5C world or a 2C world.

The table below shows the likelihood of seeing a summer where 100-400 million Europeans experience a record summer in each of the four model worlds. You can see that more than 100 million Europeans (top row) will typically see unprecedented summer heat every other year under 1.5C of warming – or in two of every three years under 2C.

And while there is a negligible likelihood of seeing a summer where more than 400 million Europeans (bottom row) experience a new record hot summer under pre-industrial conditions or in the current climate. Yet in a 2C world, we project this would happen roughly every seven years.

The table shows the likelihood in a given year of a summer where more than 100, 200, 300 and 400 million people experience a summer beyond the observed record. Numbers in parentheses show 90% confidence intervals and redder colours indicate increased likelihood. Source: King et al. (2018)

Benefits of climate action

Our analysis illustrates that in a 2C world Europeans would experience more frequent and intense heat extremes than in a 1.5C world.

Despite the fact that restricting global warming would benefit the world’s poorest more than others, our study shows that for Europe specifically, taking stronger action to reduce greenhouse gas emissions need not be a purely selfless act. The countries and peoples of Europe, especially those in southern Europe which have borne the brunt of recent heatwaves and hot summers, would benefit from reduced exposure to heat extremes if the 1.5C Paris limit is met as opposed to the 2C global warming limit.

European emissions pledges are currently rated as inadequate in reaching either the 1.5C or 2C Paris targets. Our study strongly supports progressively more ambitious reductions to be proposed at the periodic stocktakes, the first of which will probably be in 2023.

While European countries are taking stronger action to curb emissions compared to many other developed nations, it is in Europe’s own interests to maintain and strengthen these pledges.


King, A. D. et al. (2018) Reduced Heat Exposure by Limiting Global Warming to 1.5C, Nature Climate Change, doi:10.1038/s41558-018-0191-0

Dr Andrew King is a climate scientist at the University of Melbourne and Dr Markus Donat is a climate scientist at the University of New South Wales.

This article was originally published on Carbon Brief and is shared under a Creative Commons license, you can read the original here.

Cover photo by Christopher Czermak on Unsplash.
Scientists examine threats to food security upon meeting Paris climate targets

Scientists examine threats to food security upon meeting Paris climate targets

By Georgina Wade

The Paris climate agreement’s aspirational goal of limiting global warming to 1.5°C or, at least, “well below 2°C” above pre-industrial temperatures requires a further understanding of the physical and social challenges for a warming world in both temperature scenarios.  To do this, scientists are studying the impacts of various emission reductions.

A new paper from the Philosophical Transactions of the Royal Society A examined the changes in climate extremes, fresh water availability, and vulnerability to food insecurity at a 1.5°C temperature rise compared to a 2°C target.

Using a set of impacts-relevant indices and a global land surface model to examine the projected changes in weather extremes and their implications for freshwater availability and vulnerability to food insecurity, the study finds climate-related vulnerabilities increase more at 2°C global warming than 1.5°C in approximately three-quarters of countries assessed.

The Hunger and Climate Vulnerability Index used in the study incorporates how exposed a country is to climate hazards, how sensitive a country’s agriculture is to climate hazards, and a country’s ability to adapt. With these metrics and indices calculated for 122 countries across the globe, the authors reveal that some areas will be more impacted than others.

For example, heavier rainfall will affect Asia more than other regions. However, increases to drought could hit Africa and South America hardest.

Increases in either heavy rainfall or drought events imply increased vulnerability to food insecurity, but if global warming is limited to 1.5°C, this vulnerability is projected to remain smaller than at 2°C global warming in approximately 76% of developing countries. At 2°C, the countries of Oman, Bangladesh Mauritania and Yemen are projected to reach unprecedented levels of vulnerability to food security.

Helping us identify the winners and losers in a warming world, this study can assist in driving policymakers to make decisions that will limit these temperature increases. From a practical matter, current climate change mitigation efforts are insufficient to hit either temperature target, but research is giving us some idea of where our actions could take us and highlights urgent adaptation needs.


Changes in climate extremes, fresh water availability and vulnerability to food insecurity projected at 1.5°C and 2°C global warming with a higher-resolution global climate model: Richard A. Betts, Lorenzo Alfieri, Catherine Bradshaw, John Caesar, Luc Feyen, Pierre Friedlingstein, Laila Gohar, Aristeidis Koutroulis, Kirsty Lewis, Catherine Morfopoulos, Lamprini Papadimitriou, Katy J. Richardson, Ioannis Tsanis, Klaus Wyser. Phil. Trans. R. Soc. A 2018 376 20160452; DOI: 10.1098/rsta.2016.0452. Published 2 April 2018. URL http://rsta.royalsocietypublishing.org/content/376/2119/20160452

Cover photo by Dmitrij Paskevic on Unsplash
New study finds legal sector demand for climate services very likely to increase in near future

New study finds legal sector demand for climate services very likely to increase in near future

By Richard Bater

Law, and therefore legal services, will be indispensable to achieving a just transition to a low-carbon economy, as well as to ensuring that societies are resilient in the face of future climate-related risk. This renders the legal profession an essential actor, be it through crafting clear and robust legislation, ensuring compliance, or upholding constitutional rights.

New research by Acclimatise, that examines the legal sector’s demand for climate services, finds that whilst climate change has ranked very low on the sector’s agenda this has started to change during the last three years. This is partly attributable to new legislation – which increased 20-fold during the 20 years to 2017 to reach 1,200 laws – but is also due to the increasing recognition on the part of lawyers and their clients that climate change means material risk.  In future, individuals and organisations will increasingly solicit advice as to what their legal duties are vis-à-vis climate change in respect of existing (and forthcoming) laws and established legal doctrines, as well as to be shielded from climate-related litigation.

Climate change is cross-cutting and raises implications – to a greater or lesser degree – across the majority of areas of legal practice, from professional negligence, to product defect, to directors’ duties, to climate disclosure, to constitutional rights. Legal risks can arise, for example, where climate change results in organisations breaching existing compliance requirements (e.g. water quality standards).  With the reinterpretation of common law doctrines in light of climate change, failure to become adequately informed about – and manage – climate-related risk could lead directors to be in breach of directors’ duties. As Jason Betts, Partner at Herbert Smith Freehills, has observed, in order to mitigate litigation risk “companies across all sectors must ensure that the impact of climate change events – both those they may contribute to and those that might affect their businesses and profitability – are risk-assessed, costed and, where material, disclosed to the market.”

Emerging disclosure arrangements – such as those promoted by the Taskforce on Climate-Related Financial Disclosures (TCFD) – are putting climate-related risk on the boardroom agenda. By rendering climate risk a material issue that must be dealt with by organisations today, such initiatives help to bring organisational decision making on climate change into line with the timeframes within which action must be taken to limit the magnitude and risks of climate change.

Climate change adaptation, from a legal perspective, requires a highly collaborative approach; the bringing together of a range of legal skills and expertise.

– Mark Baker-Jones

Accurately disclosing climate-related risks – and proving disclosure breaches – is just one area that can require multi-disciplinary expertise, spanning climate and legal services. Indeed, as reflected by Mark Baker-Jones, more broadly “climate change adaptation, from a legal perspective, requires a highly collaborative approach; the bringing together of a range of legal skills and expertise.”  Underdevelopment of tailored climate services partly explains the hesitation of regulators to impose more stringent requirements: if regulatory provisions step too far beyond what is able to be reliably measured in a comparable way, regulators cannot be certain that regulations are being complied with and producing the change intended. Improving the robustness of harmonised and comparable climate risk metrics is essential. As Baker-Jones has also stated, “what is missing is the translation of that [climate] knowledge into practical advice and guidelines that those leading the private sector can understand and apply…Whether it is redefining the point at which liability is incurred or introducing new levels of liability where before there appeared to be none, climate change law is driving a reinterpretation of some fundamental principles of duty and responsibility.”

The study identifies several key ways in which climate services can better address the sector’s needs:

  • Develop the science of climate attribution, impact modelling, and integrated socio-economic climate impact models (including counter-factual scenario modelling);
  • Rigour, resolution, and comparability are the three highest ranking criteria of climate-related information;
  • Increase dialogue between legal services, climate scientists, and climate services;
  • Communicate climate knowledge in ways intelligible to legal audiences, including how findings correspond with legal standards of proof;
  • Develop a quality assurance regime for climate services providers.

Where climate science is evolving rapidly, there needs to be more accessible regularly-updated, spatially-nuanced communication of the state of climate (attribution) science that summarises the ‘consensus’ view to legal and other audiences in mind. A thorough record of this could become a touchstone for what is considered – and what was considered – ‘reasonably foreseeable’ at a given point in time, both guiding decision making in the present and enabling future accountability for harm.

The case study was led by Acclimatise under the MArket Research for a Climate Services Observatory (MARCO) programme. MARCO, a 2-year project coordinated by European Climate-KIC, hopes that research such as this will help to remove the barriers to the growth of the climate services industry across Europe.

Download the full case study “Legal Services” by clicking here.


Please check the MARCO website for the full suite of MARCO case studies.

The MARCO project has received funding from the European Union’s Horizon 2020 Research and Innovation Program under Grant Agreement 730272.

New study shows billions of urban citizens at risk of climate-related impacts by 2050

New study shows billions of urban citizens at risk of climate-related impacts by 2050

New research by Acclimatise, C40, the Urban Climate Change Research Network (UCCRN), and Global Covenant of Mayors for Climate & Energy reveals number of cities and citizens threatened by direct and indirect climate hazards if global greenhouse gas emissions continue unchecked. Bold climate action by cities is key to prevent 1.6 billion people being exposed to extreme heat, 800 million to coastal flooding, and 650 million to droughts. 

Billions of people in thousands of cities around the world will be at risk from climate-related heatwaves, drought, flooding, food shortages, blackouts and social inequality by mid-century without bold and urgent action to reduce greenhouse gas emissions. Fortunately, cities around the world are delivering bold climate solutions to avert these outcomes and create a healthier, safer, more equal and prosperous future for all urban citizens.

This new research predicts how many urban residents will face potentially devastating heat waves, flooding and droughts by 2050 if global warming continues on its current trajectory. The Future We Don’t Want – How climate change could impact the world’s greatest cities also looks at indirect climate impacts and estimates how climate change under a ‘business-as-usual scenario’ will impact urban food security and energy systems as well as the urban poor, who are most vulnerable to climate change.

Headline findings include that, by 2050

The Future We Don’t Want also contains concrete examples of bold climate solutions that cities are delivering, which, if adopted at-scale, could help prevent the worst impacts of climate change. The research was launched at the Adaptation Futures conference in Cape Town, where representatives of cities around the world are sharing ideas on how to prepare and adapt their cities for the effects of climate change.

“For decades, scientists have been warning of the risks that climate change will pose from increasing global temperatures, rising sea levels, growing inequality and water, food and energy shortages. Now we have the clearest possible evidence of just what these impacts will mean for the citizens of the world’s cities, said Mark Watts, Executive Director C40 Cities. “This is the future that nobody wants. Our research should serve as a wake-up call on just how urgently we need to be delivering bold climate action.”

“For most C40 cities, the impacts of climate change are not a far-off threat. From Cape Town to Houston, Mayors are seeing severe droughts, storms, fires and more,” said Antha Williams, Head of Environmental Programs at Bloomberg Philanthropies and C40 Board Member, “As this report shows, C40 mayors are on the front line of climate change, and the actions they take today–to use less energy in buildings, transition to clean transportation and reduce waste—are necessary to ensure prosperity and safety for their citizens.”

“Climate change is already happening, and the world’s great cities are feeling the impact. Cape Town is facing an unprecedented drought, but thanks to the efforts of our citizens to adapt, we have averted Day Zero, when we would have had to switch off most taps,” said Patricia de Lille, Executive Mayor of Cape Town and Global Covenant of Mayors for Climate & Energy Board Member. “The lessons from Cape Town, and from this important new research is that every city must invest today in the infrastructure and policies that will protect citizens from the future effects of our changing global climate.”

City climate solutions featured in the report include:

  • Extreme heat: Seoul has planted 16 million trees and expanded its green space by 3.5 million m2. The city has also set up shaded cooling centres for those unable to access air conditioning.
  • Flooding: New York City is improving coastal flood mapping, strengthening coastal defences and building smaller, strategically placed local storm surge barriers around the city.
  • Drought: São Paulo has set up reward schemes to incentivise citizens to use less water, whilst investing in the city’s pipeline system to reduce water leakage.
  • Urban food security: Paris plans to establish 33 hectares of urban agriculture within the city’s boundaries by 2020. By 2050, 25 percent of the city’s food supply will be produced in the Île-de-France region
  • Energy Supply: London is improving drainage infrastructure to ensure key infrastructure can withstand heavy flooding, whilst also encouraging decentralised energy supply to reduce the risk of blackouts if any one power source is damaged.
  • Extreme heat & poverty: Lima’s Barrio Mío programme created a poverty map of the city helping policy makers to focus resources on the most vulnerable and under-served areas where people are most exposed to heat risks.

Download the full report by clicking here.


Cover photo by Arto Marttinen on Unsplash
Rising heat wave risk looms for Pakistan

Rising heat wave risk looms for Pakistan

By Saleem Shaikh

Average temperatures and heatwave frequency will keep rising in Pakistan, say researchers as the country has struggled to come to grips with soaring temperatures in recent weeks.

A team of international researchers, who say their study is the first to show the country’s heat-wave trajectory forecasts a 75 per cent increase in heat waves by 2030, a 189 per cent by 2060 and a 277 per cent increase by 2090. “This means the country will experience around 12 heat wave events annually by 2030, 20 such events by 2060 and 26 events by 2090,” says Wajid Nasim, lead author and associate professor at the department of environmental sciences, COMSATS Institute of Information Technology.

“Extreme weather events will become more frequent, prolonged and intense” –Wajid Nasim

The study, published this month (June) in Atmospheric Research, shows that Pakistan was hit by 126 heat waves of varying durations over the 1997‒2015 period for an average of seven heat waves per year. This year, at least 65 people have died in the capital Karachi, and temperatures in parts of the country have exceeded 40 degrees Celsius for weeks, reaching a record-breaking 50.2 degrees in April.

These extreme events will become more frequent, prolonged and intense, Wajid tells SciDev.Net.

He and his team relied on historical datasets of heat wave events and daily maximum temperature variations for the study period. The data was drawn from the Pakistan Meteorological Department (PMD) through 29 weather stations in the provinces of Punjab, Sindh and Baluchistan.

Heat waves are defined as spikes in temperature beyond 45 degrees Celsius in the plains, and beyond 40 degrees Celsius in hilly areas. Average maximum temperatures of 42 degrees Celsius, with a 5‒6 degree rise lasting eight days or more, are also classed as heat waves.

The researchers warn that the trend carries risks for crop yields as well as human health. Heat waves raise the irrigation needs of summer crops, increase droughts and contribute to groundwater depletion in the country.

Rising average temperatures during pre-monsoon months (March, April and May), during which most of the heat waves are expected to occur in the coming decades, could lead to early maturity of winter crops including wheat, maize, potato and lentils — and a consequent decline in crop yields.

Higher temperatures during these months will also increase irrigation needs for various summer crops including rice, cotton, sugarcane and mango. A rapid decline in soil moisture and higher levels of surface water evaporation are contributing factors.

Ghulam Rasul, director-general of the PMD, says the findings demand an adaptation response from the government with a focus on early-warning systems.

Rasul observes that March and April used to be cool to mild months, which helped the soil to retain moisture.

“It is startling to observe March becoming warmer every year. The high temperatures we used to record in the peak summer months (June and July) about eight years ago are now being recorded in March,” he tells SciDev.Net.

In June 2015, more than 1,200 people died of heat-related illnesses in the southern port city of Karachi when temperatures soared to 49 degrees Celsius. In May 2010, the city of Mohenjo Daro, also in southern Pakistan recorded 53.5 degrees Celsius, the highest ever recorded in Asia.

Nasim says various adaptation measures, such as building the capacity of individuals and communities to respond to heat stress during heat waves, and campaigns to raise heat-health awareness, are imperative.


This piece was produced by SciDev.Net’s Asia & Pacific desk. This article was originally published on SciDev.Net. Read the original article.

Cover photo by Kamran Ali/Wikimedia (CC BY-SA 3.0): Vegetable and Fruit Market of Layyah at twilight. 2007.