Global Warming is at Tipping Point

Scientists have warned world temperatures are likely to rise by more than two degrees Celsius this century, surpassing a “tipping point” that the United Nations brokered global climate agreement aims to avert.

A study published in the journal Nature Climate Change shows a 90 per cent chance that temperatures will increase this century by 2.0°C to 4.9°C.

Reuters Newsagency reports researchers at the University of Washington found only a five per cent chance that warming could be at or below 2.0°C, one of the targets set by the 2015 Paris Agreement on climate change, aimed at limiting emissions of greenhouse gases that warm the planet.

Missing that target would have dramatic consequences on people’s livelihoods, such as prolonged periods of drought and rising sea levels, said Professor Adrian Raftery, the lead author of the study who is from the University of Washington.

The study uses statistical projections based on total world population, GDP per capita and the amount of carbon emitted for each dollar of economic activity, known as carbon intensity.

“Our analysis shows that the goal of two degrees is very much a best-case scenario,” said Professor Raftery.

“It is achievable, but only with major, sustained effort on all fronts over the next 80 years.”

According to the UN Environment Program (UNEP), world greenhouse gas emissions, mainly from burning fossil fuels, are now about 54 billion tonnes a year and should be cut to 42 billion by 2030 to get on track to stay below 2.0°C.

“Countries need to change the economic incentives for producing carbon, for example by introducing a carbon tax, and encourage innovation that would improve energy efficiency,” he said.

“We should be learning more from countries that are particularly carbon-efficient, like France, which has a very low-carbon transport infrastructure.”

A second new study, just released, takes a different approach, analysing how much global warming the world has already committed to, since the warming due to some emissions has not yet arrived.

Nonetheless, with the planet at a so-called energy imbalance, that warming is inevitably coming, and the study, conducted by Thorsten Mauritsen of the Max Planck Institute for Meteorology in Germany and Robert Pincus of the University of Colorado, Boulder, finds that it probably pushes us several slivers of a degree beyond where we are now.

The upshot is that we may already have firmly committed to 1.5°C of warming even if emissions were to stop immediately and entirely, which is not going to happen.

One scenario presented in the study finds a 13 per cent chance that 1.5°C is already on the way; another finds a 32 per cent chance.

Again, the margin for avoiding two degrees Celsius narrows accordingly