January 2023 – Cabot Institute for the Environment blog

Climate change is threatening Madagascar’s famous forests – our study shows how serious it is

Posted on January 20, 2023March 27, 2023 by amanda.woodman-hardy

Urgent action is needed to protect Madagascar’s forests.
Rijasolo/AFP via Getty Images

Global climate change doesn’t only cause the melting of polar ice caps, rising sea levels and extreme weather events. It also has a direct effect on many tropical habitats and the animals and plants that inhabit them. As fossil fuel emissions continue to drive climate change, large areas of land are forecast to become much hotter and drier by the end of this century.

Many ecosystems, including tropical forests, wetlands, swamps and mangroves, will be unable to cope with these extreme climatic conditions. It is highly likely that the extent and condition of these ecosystems will decline. They will become more like deserts and savanna.

The island nation of Madagascar is of particular concern when it comes to climate change. Of Madagascar’s animal species, 85% cannot be found elsewhere on Earth. Of its plant species, 82% are unique to the island. Although a global biodiversity hotspot, Madagascar has experienced the highest rates of deforestation anywhere in the world. Over 80% of its original forest cover has already been cleared by humans.

This has resulted in large population declines in many species. For example, many species of lemurs (Madagascar’s flagship group of animals) have undergone rapid population decline, and over 95% of lemur species are now classified as threatened on the International Union for Conservation of Nature (IUCN) Red List.

Drier conditions brought about by climate change have already resulted in widespread bush fires throughout Madagascar. Drought and famine are increasingly severe for the people living in the far south and south-western regions of the island.

Madagascar’s future will likely depend profoundly on how swiftly and comprehensively humans deal with the current climate crisis.

What we found

Our study investigated how future climate change is likely to affect four of Madagascar’s key forest habitat types. These four forest types are the dry deciduous forests of the west, humid evergreen forests of the east, spiny bush forests of the arid south, and transitional forests of the north-west corner of the island.

Using computer-based modelling, we simulated how each forest type would respond to climate change from the current period up to the year 2080. The model used the known distribution of each forest type, and current and future climatic data.

We did this under two different conditions: a mitigation scenario, assuming human reliance on greenhouse gas reduces according to climate commitments already made; and an unmitigated scenario, assuming greenhouse gas emissions continue to increase at their current rate.

Our results suggest that unmitigated climate change will result in declines of Madagascar’s forests. The area of land covered by humid forest, the most extensive of the four forest types, is predicted to decrease by about 5.66%. Dry forest and spiny bush are also predicted to decline in response to unmitigated climate change. Transitional forest may actually increase by as much as 5.24%, but this gain will almost certainly come at the expense of other forest types.

We expected our model to show that mitigating climate change would result in net forest gain. Surprisingly, our results suggest entirely the opposite. Forest occurrence will decrease by up to 5.84%, even with efforts to mitigate climate change. This is because global temperatures are forecast to increase under both mitigated and unmitigated scenarios.

These predicted declines are in addition to the huge losses of forest already caused by ongoing deforestation throughout the island.

It looks as if the damage has already been done.

Climate change, a major threat

The results of our research highlight that climate change is indeed a major threat to Madagascar’s forests and likely other ecosystems worldwide. These findings are deeply concerning for the survival of Madagascar’s animals and plants, many of which depend entirely on forest habitat.

Not only will climate change decrease the size of existing forests, changes in temperature and rainfall will also affect the amount of fruit that trees produce.

A Lemur on tree in the forest. — Madagascar lemurs and other animal and plant species may become extinct if the forests disappear.
Rijasolo/AFP

Many of Madagascar’s animals, such as its lemurs, rely heavily on fruit for food. Changes in fruit availability will have serious impact on the health, reproductive success and population growth of these animals. Some animals may be able to adapt to changes in climate and habitat, but others are very sensitive to such changes. They are unlikely to survive in a hot, arid environment.

This will also have serious knock-on effects for human populations that depend on forests and animals for eco-tourism income. Approximately 75% of Madagascar’s population depends on the forest and subsistence farming for survival, and the tourism sector contributes over US$600 million towards the island’s economy annually.

To ensure that Madagascar’s forests survive, immediate action is needed to end deforestation, protect the remaining patches of forest, replant and restore forests, and mitigate global carbon emissions. Otherwise these remarkable forests will eventually disappear, along with all the animals and plants that depend on them.

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This blog is written by Daniel Hending, Postdoctoral Research Assistant Animal Vibration Lab, University of Oxford and Cabot Institute for the Environment member Marc Holderied, Professor in Sensory Biology, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Marc Holderied

Detectable impacts of Climate Change in the UK; a new review for the next Climate Change Risk Assessment

Posted on January 17, 2023March 29, 2023 by janet.crompton

2022 was another year of “unprecedented” weather. Provisional figures indicate that it was the warmest so far recorded, with almost every month hotter than average. Much of the country had a notably mild New Year, despite the cold snap in mid-December. This was preceded by the third warmest autumn on record, and that by a scorching summer, with the hottest day ever recorded in July. But summer’s heat waves were also accompanied by a rise in the number of daily deaths across the country. People around the world are becoming increasingly more aware of events like these, and their impact in the UK is particularly concerning amidst the ongoing cost-of-living, energy, and NHS crises.

Aerial view of the Wennington wildfire, London, 19 July 2022. Source: Harrison Healey, Wikimedia Commons (CC BY 3.0).

Ahead of the Fourth UK Climate Change Risk Assessment (CCRA4), the Climate Change Committee (CCC) are asking what we know about the impact of past and present climate change on natural and human systems here in the UK specifically. At the global level, the 2021 IPCC sixth assessment working group I (AR6 WGI) report concluded: “It is unequivocal that human influence has warmed the atmosphere, ocean and land.” This single sentence has been informed by decades of research by people at the cutting edge of climate science, and the evidence to support it has grown stronger in every IPCC report since they began. The report goes on to say: “Human-induced climate change is already affecting many weather and climate extremes in every region across the globe.” In last year’s follow-up AR6 WGII report on impacts, adaptation, and vulnerability, an extensive assessment of the science led to the conclusion that the magnitude and proliferation of extremes caused by human-induced climate change were having widespread, adverse impacts on both nature and people. Last summer’s heatwaves, and the concurrent dangers to health, homes, and the environment, were a graphic illustration of the nature of such human-induced impacts.

The study of impacts that informed this conclusion is the remit of climate scientists who specialise in “detection and attribution”. This is about looking at what is changing around us and being able to pinpoint the cause(s) – and particularly, whether human-induced climate change is at the root. To inform CCRA4, the CCC have commissioned a joint Bristol and Exeter University team to conduct a comprehensive review of the detection and attribution of climate change in the UK. The first part will cover the detection and attribution of weather and climate changes in the UK, relevant to specific “Climate Impact Drivers”. The second will cover attribution of impacts on societal, infrastructural, economic, and biodiversity sectors. We aim to find out what studies have been done so far, where the gaps are, and whether they can be filled, or if they would require substantial new methodological or data advances. We aim to identify variables which are key drivers of multiple impacts, and, importantly, where further attribution analysis is needed – especially when the impacts are critical for UK risk.

Detection and attribution is a rapidly evolving field, with focus only relatively recently moving from meteorological attribution (e.g., weather extremes) to impact attribution (e.g., consequences for humans and ecosystems). Our systematic review of the literature and final report will be key to tying it all together, especially with the UK focus required by the CCC. But to be able to present the most up-to-date findings, and thus make informed recommendations, we need to ensure that we have considered all relevant studies. So, if you, or someone you know, has published on this topic – whether UK specific or not – we’d like to know about it! Help shape and inform the next UK Climate Change Risk Assessment.

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This blog was written by Regan Mudhar, Professor Dann Mitchell (University of Bristol), Professor Richard Betts and Professor Peter Stott (University of Exeter/UK Met Office).

Four ways winter heatwaves affect humans and nature

Posted on January 11, 2023April 14, 2023 by janet.crompton

Temperature anomaly in Europe, Jan 1. Much of the continent was 10°C or more (dark red and grey) above the long-term average.
WX Charts, CC BY-NC

An extreme winter heatwave meant countries across Europe experienced a record-breaking New Year’s Day. New daily temperature records for the month of January were set in at least eight countries: Belarus, Czechia, Denmark, Latvia, Liechtenstein, Lithuania, Netherlands and Poland.

In many cases the temperatures were not just breaking the old highs, but smashing them by massive margins. On a typical January day in Warsaw, Poland, temperatures would barely go above freezing, yet the city recently experienced 19℃, breaking the previous January high by 5.1℃.

New January records were set at thousands of individual stations in many other countries such as 25.1℃ at Bilbao airport in Spain, 0.7℃ hotter than the previous record set only last year. Large areas of central and Eastern Europe experienced temperatures 10℃ to 15℃ warmer than average for this time of year – and that has persisted through the week.

When Europe experienced extreme heat in July of last year, more than 20,000 died. Fortunately winter heatwaves are much less deadly, but they can still affect both human society and natural ecosystems in many ways.

1. Less energy is needed

In Europe deaths due to cold weather vastly outweigh those caused by extreme high temperatures – in the UK there are ten times more. Warmer winters will reduce this excess mortality and, with the current cost-of-living crisis, many will have been relieved that a heatwave meant less energy was needed to heat their homes.

Electricity demand is influenced by things like the time of day, the day of the week and socio-economic factors like the COVID pandemic or the war in Ukraine. The weather also makes a difference. For example, in Poland and the Netherlands demand was noticeably lower than average, especially since January 1 was a Sunday. The extent of the heatwave also meant countries could refill some of their winter gas reserves, or large batteries.

Energy consumption in Poland December 28 to January 5. The red line shows the 2022-2023 heatwave period, and the grey lines show available data from 2015-2022.
Hannah Bloomfield / data: transparency.entsoe.eu, Author provided

2. Reduced yields for some crops

Winter warm spells don’t always have such a positive impact though. For instance a lack of snow in the mountains affects agriculture and can reduce crop yield, since snow creates an insulating blanket that prevents frost from penetrating into the soil. This means snow can actually increase soil moisture more than rainfall, thus improving growing conditions later in the season.

The big snow melt in spring time replenishes reservoirs and allows hydroelectricity generation, but unexpected snow melt can lead to flooding. Changes to the timings of these events will require preparation and adaptation to enable a steady supply of water to where we need it.

Warmer temperatures will create longer growing seasons in many regions. This is not always the case though. A recent study showed that for alpine grasslands an earlier growing season (the point when snow has melted entirely) leads to ageing and browning of the grasses in the later part of the summer.

3. The snow economy is in trouble

The heatwave caused ski resorts across the Alps to close in what should be their busiest time of year. In January the slopes would be expected to have a good covering of snow – but instead we saw green grassy fields.

This hits the local economy where many people rely on winter sports tourism. Events such as the Adelboden alpine ski World Cup are relying on artificial snow, which comes with a further environmental cost increasing the carbon footprint of ski resorts and requiring a large water supply. Indeed, the Beijing winter Olympics used the equivalent of daily drinking water for 900 million people to generate the artificial snow it required.

4. Animals out of sync with the climate

We humans are perhaps fortunate, as we are able to adapt. Some ski resorts have already opened mountain bike trails in winter to offer alternative tourism, but wildlife and ecosystems cannot adjust so rapidly.

In the mountains many species, such as ptarmigan and mountain hares, change their colouring for winter to camouflage in the white snow. The timing of this change is determined by length of day – not the temperature or amount of snow. These creatures are at greater risk of being preyed on when it is warmer.

White rabbit, brown background — Mountain hares are dressed for a climate that has changed.
Mark Medcalf / shutterstock

Over the past century heat extremes in Europe have increased in intensity and frequency. Both the general warming and heatwave events have been firmly attributed to humans.

Future projections suggest these trends will continue and heatwaves in both summer and winter will get hotter, last longer, and occur more often. We need to learn to adapt for these changes in all seasons and think about the impacts on everyone – and everything – on our planet.

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This blog is written by Cabot Institute for the Environment members Dr Vikki Thompson, Senior Research Associate in Geographical Sciences, University of Bristol and Dr Hannah Bloomfield, Postdoctoral Researcher in Climate Risk Analytics, University of Bristol. This article is republished from The Conversation under a Creative Commons license. Read the original article.