Climate inaction makes 4 degree C rise likely by 2100 or earlier

Doing nothing to curb greenhouse gas emissions makes it likely we’ll see global warming of more than 4 degrees C by 2100, according to researchers at the Met Office Hadley Centre.

If that happens, add scientists gathering at a climate conference in Oxford this week, we will no longer recognise our planet … because it will be a substantially different one from what we live on today.

The conference — 4 degrees & beyond — runs through tomorrow and features presentations from researchers around the globe about how that level of warming would likely affect agriculture, food and water security, ecosystems and, essentially, everything about life as we know it.

“Four degrees of warming, averaged over the globe, translates into even greater warming in many regions, along with major changes in rainfall,” Met Office Head of Climate Impacts Richard Betts told conference attendees on Monday. “If greenhouse gas emissions are not cut soon, we could see major climate changes within our own lifetimes.”

If emissions remain high, we could see warming of 4 degrees C by the 2070s, under the Met Office’s “best guess.” In the plausible worst-case scenario, that degree of warming could be reached by 2060.

In some parts of the world, Betts said, warming could be significantly higher … by as much as 10 degrees C or more.

Among the impacts projected by the Met Office research:

• The Arctic could warm by up to 15.2 degrees C, under a high-emissions scenario;
• Western and southern Africa could experience both drying and warming of up to 10 degrees C;
• Other land areas around the globe could warm by 7 degrees C or more;
• Rainfall could decrease by 20 per cent or more in some areas, particularly in western and southern Africa, Central America, the Mediterranean and parts of coastal Australia; and
• Other areas such as India could see rainfall increase by 20 per cent or more, leading to greater risk of river flooding.

“Together these impacts will have very large consequences for food security, water availability and health,” Betts said. “However, it is possible to avoid these dangerous levels of temperature rise by cutting greenhouse gas emissions. If global emissions peak within the next decade and then decrease rapidly it may be possible to avoid at least half of the four degrees of warming.”

Other researchers speaking at the Oxford conference offered a number of other likely impacts if the planet warms by 4 degrees C or more:

• Unless the UK takes steps to increase water supplies and storage capacity, some regions could face the potential for supply failures;
• By mid-century, annual rainwater runoff could decrease substantially across much of Europe, the Middle East, North Africa, the southwest US, Mexico and southern South America;
• While there remains some opportunity for adapation in agriculture, the higher temperatures rise, the greater become the risks of crop failure;
• In some places, like Mauritius, adaptation for certain crops such as sugarcane will be impossible; and
• Much of Africa will also have scarce capacity for adaptation in agriculture.

Sub-Saharan Africa in particular faces grave risks if climate change continues, according to researchers Philip Thornton and Peter Jones.

“(T)he changes in a plus five-degree world would be way beyond experience,” they warned in their conference presentation on agriculture in Sub-Saharan Africa. “We had better avoid it at all costs.”