Alarming reports on world-wide warming trends for the first half of 2016 show the Earth approaching the 1.5°C long-term target for average warming established in the Paris Agreement, underscoring the urgency of efforts to ratify the agreement this year and rapidly improve on the limited commitments behind the global deal.
“So far, 2016 has seen an average 1.2°C warming above 1850-1900 levels, a big increase on the 1.06°C warming last year, in turn a big increase on 0.88°C warming the year before,” reports climate and energy blogger Gerard Wynn. “March 2016 was an all-time record month, 1.46°C warmer than pre-industrial levels, already near the 1.5°C target set eight months ago. Since March, global average temperatures have fallen, but monthly averages have remained more than 1°C above the 1850-1900 baseline through the first six months of the year.”
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The recent temperature record shows “an aggressive warming trend, in almost a straight line since the mid-1970s, after removing annual natural variation due to events like El Niño,” Wynn warns. “It puts into perspective recently stalled growth in annual emissions—a great achievement in itself, but only a first step in addressing the climate change problem.”
Wynn’s calculations echo earlier concerns from British scientists, and others dating back to the Paris conference itself, about whether the 1.5°C long-term target is attainable. Writing late last month in the journal Scientific Reports, Dr. Chris Huntingford and Lina M. Mercado of the University of Exeter questioned whether average global temperatures can now be stabilized at or below 1.5ºC, even if all carbon emissions ceased immediately, given recent record increases in atmospheric CO2.
Two factors account for their conclusion that “even for current levels of atmospheric GHGs, there is a very high probability that the planet is committed to a mean warming over land greater than 1.5 °C.” One is that the oceans will eventually absorb less heat as the climate system approaches thermal equilibrium. The other is that the atmosphere is warming faster over large land masses than over the oceans. “Such warming could be greater than 2.0 °C,” the scientists add, “and in particular for large continental regions away from coastlines.”
Against that likelihood, Huntingford said the world may be lucky to achieve the primary Paris goal of keeping warming “well below” 2.0ºC. And he claimed decision-makers should not commit extraordinary resources in a vain effort to reach the “aspirational” lower target.
“I think there needs to be a very thoughtful debate about what’s to be gained at these different temperature levels, if approaching the lower levels meant severely damaging the economy,” he told BBC News.
“Every climate scientist realizes that when you write that ‘we have to get emissions down to hit this target,’ that could potentially push the world into a global recession,” Huntingford said. [Editor’s note: No, not every climate scientist assumes that.] “So we need to be really clear about what’s to be gained by aiming for 1.5 that might be extremely difficult for society, rather than 2.0°.”
