Climate Change on Land

Climate Change on Land

We looked at the impact of climate change on the sea in a recent blogpost.  That included issues of coastal flooding, storm surges and salination. In this one, we look at the more direct impacts on land.

recent IPCC report noted that warming is generally higher over land than over the ocean.  Warming greater than the global annual average is being experienced in many land regions and seasons, including two to three times higher in the Arctic.  Many ecosystems and some of the services they provide have already changed due to global warming.

If global temperatures rise by 2°C then we can expect increases in hot days in most inhabited regions, heavy precipitation in several regions and the drought and precipitation deficits in some regions. Hot days in mid-latitudes warm by up to about 3°C at global warming of 1.5°C and about 4°C at 2°C; cold nights in high latitudes warm by up to about 4.5°C at 1.5°C and about 6°C at 2°C . The number of hot days is projected to increase in most land regions, with highest increases in the tropics.

Risks from heavy precipitation are projected in several northern hemisphere high-latitude and/or high-elevation regions, eastern Asia and eastern North America. Heavy precipitation associated with tropical cyclones is also projected to be higher.

And remember that the Climate Action Tracker forecast based on the Paris Conference commitments was for a temperature rise of 3°C.

PATTERN OF WARMING

Global average precipitation is expected to rise by about 3% to 5% by the year 2100 (IPCC) but this will not be consistent across the world:

  • Much of the increase in precipitation is expected to occur at high latitudes.
  • Low- and mid-latitude regions, are expected to suffer from more frequent and more severe droughts; dry conditions and warmer temperatures produce longer “fire seasons”.
  • Increased snowfall near both poles may offset some of the melting of glaciers and ice sheets in these regions by adding fresh ice to the tops of these features.
  • Some presently dry regions may welcome increased rainfall, but if this could manifest as heavy rainfall that causes flooding interspersed with more frequent droughts.
  • Hurricane seasons may start earlier and end later, providing more time for storms to occur. Storms may move into higher latitudes as ocean waters warm – the unprecedented occurrence of Hurricane Catarina in the South Atlantic along the coast of Brazil in March 2004 may be an ominous portent of things to come.

EXTREME WEATHER

Global warming is projected to lead to an increase in extreme weather events. Higher levels of humidity create increasingly unstable weather patterns.  More floods, storms and droughts; more wildfires. Asian monsoons become disrupted. Some places, notably Australia, experience many different extreme events in quick succession.

We will look into the likely patterns of extreme weather events in a future post.

MIGRATION

Populations at disproportionately higher risk of adverse consequences include disadvantaged and vulnerable populations, some indigenous peoples, and local communities dependent on agricultural or coastal livelihoods. Regions at disproportionately higher risk include Arctic ecosystems, dryland regions, small island developing states, and Least Developed Countries. Poverty and disadvantage are expected to increase in some populations as global warming increases (IPCC).

We will examine the impact of climate change on migration in a later post.

WATER

Research by the Met Office and Leeds University shows that global heating could bring many more bouts of severe drought as well as increased flooding to Africa than previously forecast.  The continent will experience many extreme outbreaks of intense rainfall over the next 80 years, triggering floods, storms and disruption of farming. In addition, these events are likely to be interspersed with more crippling droughts during the growing season also damaging crop and food production. The wet extreme will get worse, but the appearance of dry spells during the growing season will also get more severe.

The rate glaciers are melting in the Himalayas has doubled in just 20 years, according to a study which examined 40 years of satellite data.  Glaciers have been losing more than a vertical foot and a half of ice each year since 2000. Eight-hundred million people depend on seasonal runoff from Himalayan glaciers for irrigation, hydropower and water. There is currently more run-off during warm seasons but within the next few decades this will decrease as the glaciers lose mass, leading to water shortages. Similar effects are expected in the Andes.

ECOSYSTEMS

Impacts on biodiversity and ecosystems, including species loss and extinction, are projected to be higher at global warming of 2°C. Of 105,000 species studied, 18% of insects, 16% of plants and 8% of vertebrates are projected to lose over half of their climatically determined geographic range for global warming of 2°C . There are also increased impacts associated with other biodiversity-related risks such as forest fires and the spread of invasive species.

High-latitude tundra and boreal forests are particularly at risk of climate change-induced degradation and loss, with woody shrubs already encroaching into the tundra and this will proceed with further warming.  (IPCC)

AGRICULTURE

Warming of 2°C is projected to result in higher net reductions in yields of maize, rice, wheat, and potentially other cereal crops, particularly in sub-Saharan Africa, Southeast Asia, and Central and South America, and in the CO2-dependent nutritional quality of rice and wheat. Reductions in projected food availability are larger in the Sahel, southern Africa, the Mediterranean, central Europe, and the Amazon. Livestock are projected to be adversely affected with rising temperatures, depending on the extent of changes in feed quality, spread of diseases, and water resource availability. (IPCC)

The recent heatwave in Europe caused crop damage in France, the European Union’s largest grain growing nation. Grains such as rapeseed and wheat are in their crucial pre-harvest period making them more fragile to heat stress. Water restrictions, including for irrigation, are in place in one fifth of mainland France’s 96 administrative departments.

The UK Climate Change Risk Assessment 2017 noted that climate change will present risks and opportunities for domestic production, with the resilience of UK food systems dependent on the stewardship of natural resources including soils. The report concludes that there is a need for policy intervention over the next five years to manage the potential impacts of these risks on food prices in the UK.

There are odd positive implications and new opportunities too. In some areas of Argentina, farming conditions will improve due to heavier rainfall in traditionally dry areas.

PESTS

The UK Climate Change Risk Assessment 2017 also describes how new and emerging pests and diseases – including invasive non-native species – have the potential to cause severe impacts on people, animals and plants. It concludes we need to improve our understanding of how climate change will affect the threat of pests and diseases.

Research suggests that even slight climate warming could increase malaria riskto hundreds of thousands, if not millions, of people in areas that are currently too cold for malaria parasites to complete their development. The rate of malaria transmission to humans is strongly determined by the time it takes for the parasites to develop in the mosquito. The quicker the parasites develop, the greater the chance that the mosquito will survive long enough for the parasites to complete their development and be transmitted to humans.

TREES

Trees absorb and store carbon dioxide emissions, so planting billions of trees across the world is by far the biggest and cheapest way to tackle the climate crisis. Recent analysis found there are 1.7bn hectares of treeless land on which 1.2tn native tree saplings would naturally grow. That area is about 11% of all land and equivalent to the size of the US and China combined. Tropical areas could have 100% tree cover, while others would be more sparsely covered, meaning that on average about half the area would be under tree canopy.

In practice, things are moving in the opposite direction.

Deforestation in Brazil’s portion of the Amazon rainforest rose more than 88% in June compared with the same month a year ago, the second consecutive month of rising forest destruction under the new president Bolsanaro.  According to data from Brazil’s space agency, deforestation in the world’s largest tropical rainforest totaled 920 sq km (355 sq miles).

The Congo Basin is the second-largest rainforest on Earth is also subject to deforestation. Not only does that mean that the forests are less able to take CO2out of the atmosphere, carbon that has been locked up in the Congo’s soils for hundreds to thousands of years is starting to seep out. Soils hold a tremendous amount of carbon—more than the atmosphere and living vegetation combined. About a third of that carbon resides in soils in the tropics, areas that are undergoing profound changes due to population growth, industry, and agriculture.

NEXT

In our next post on climate change, we will look at the impact of warming world on natural defences. If you have views on any of the issues in this field, please do contact us and we can give you the opportunity to express them.

Written by Huw Williams, SAMI Principal

Image by Jody Davis from Pixabay

The views expressed are those of the author and not necessarily of SAMI Consulting.

SAMI Consulting was founded in 1989 by Shell and St Andrews University. They have undertaken scenario planning projects for a wide range of UK and international organisations. Their core skill is providing the link between futures research and strategy.

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