New climate change warning

LIMITING global warming to 2°C will not prevent destructive and deadly climate impacts, as once hoped, dozens of experts concluded in a score of scientific studies released yesterday.

A world that heats up by 2°C – long regarded as the temperature ceiling for a climate-safe planet – could see mass displacement due to rising seas, a drop in per capita income, regional shortages of food and fresh water, and the loss of animal and plant species at an accelerated speed.

Poor and emerging countries of Asia, Africa and Latin America will get hit hardest, according to the studies in the British Royal Society’s Philosophical Transactions A.

“We are detecting large changes in climate impacts for a 2°C world, and so should take steps to avoid this,” lead editor Dann Mitchell, an assistant professor at the University of Bristol, said.

The 197-nation Paris climate treaty, inked in 2015, vows to halt warming at well under 2°C compared with mid-19th century levels, and try to cap the rise at 1.5°C.

Climate change was the most systemic threat to humankind, UN secretary-general Antonio Guterres said on Thursday.

With only one degree of warming so far, Earth has seen a crescendo of droughts, heat waves, and storms ramped up by rising seas. Voluntary national pledges made under the Paris pact to cut CO2 emissions, if fulfilled, would yield a 3°C world at best.

The treaty also requires that – by the end of the century – humanity stop adding more greenhouse gases to the atmosphere than oceans and forests can absorb, a threshold known as “net zero emissions”.

“How fast we get to a 2°C world is critical,” Mitchell said.

“If it only takes a couple of decades, we will be in trouble because we won’t have time to adapt to the climate.”

Researchers led by Felix Pretis, an economist at the University of Oxford, predict that two degrees of global warming will see GDP per person drop, on average, 13% by 2100, once costly climate change impacts are factored in.

A 2°C world would also show significant negative impact on the rates of economic growth, Pretis said.

Under a 1.5°C scenario, he added, growth projections were near indistinguishable from current conditions.

Under a 2°C scenario, oceans rise about half a metre over the course of the 21st century, but well over a metre by 2300, another study found.

“When the planet warms, it takes the ocean hundreds, if not thousands, of years to fully respond,” lead author Robert Nicholls, a professor of coastal engineering at the University of Southampton, said.

That is bad news for 500 million people living in highly vulnerable low-lying deltas, mainly in Asia, along with about 400 million people in coastal cities, many of which are already sinking due to over-construction or collapsing water tables.

Even in a 2°C world, the number of people affected yearly by flooding could approach 200 million by 2300, the study calculated.

Two degrees of warming would spare humanity much misery compared with our current trajectory, but would still lead to increased drought, flooding, heat waves and the disruption of weather patterns.

Some regions would be hit worse than others, as would countries with rainfall-dependent agriculture, a team led by Richard Betts, head of climate impacts research at the University of Exeter, found.

The countries that showed the greatest increase in vulnerability to food insecurity when moving from the present-day climate to 2°C global warming are Oman, India, Bangladesh, Saudi Arabia and Brazil, he said.