Climate Change: Key points of the UN assessment

Of all the troubling news in the Intergovernmental Panel on Climate Change (IPCC) report released recently, one warning will surely generate the most discussion: under all scenarios examined, Earth is likely to reach the crucial 1.5℃ warming limit in the early 2030s. As the report makes clear, global warming of 1.5℃, and then 2℃, will be exceeded […]

Of all the troubling news in the Intergovernmental Panel on Climate Change (IPCC) report released recently, one warning will surely generate the most discussion: under all scenarios examined, Earth is likely to reach the crucial 1.5℃ warming limit in the early 2030s.

As the report makes clear, global warming of 1.5℃, and then 2℃, will be exceeded this century unless we make deep cuts to CO₂ and other greenhouse gas emissions in coming decades. Climate change and its consequences are already being felt. Beyond 1.5℃, the situation is likely to rapidly deteriorate

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How 1.5℃ warming is measured

The warming is measured as a global average over 20 years, to account for natural variability in the system.

Before global average temperatures officially reach 1.5℃ warming, we can expect quite a few years will exceed that limit. In fact, global temperatures exceeded 1.5℃ warming during individual months at the peak of the 2015-16 El Niño.

The industrial era – and associated greenhouse gas emissions – started in the 1700s. But there is almost no observed climate data on land outside Europe before the mid-19th century.

According to the latest IPCC findings, Earth’s average temperature in the last decade was 1.09℃ warmer than the pre-industrial baseline. Obviously, this goes most of the way to 1.5℃ of warming. The IPCC says this warming is unequivocally the result of human influence.

The Arctic is warming up faster:

In the Arctic, the average temperature on the coldest days is expected to increase at about triple the rate of global warming across the planet as a whole

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Carbon sinks are saturated:

The capacity of forests, soil and oceans to absorb CO2 produced by humans is likely to weaken with the continuation of greenhouse gas emissions

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Extreme weather events:

There will be an unprecedented rise in heatwaves and torrential rains. The ashphalt-melting heatwaves in Canada (near 50°C) would be “virtually impossible” if not for climate change.

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Rising seas and “irreversible” ice melting:

The changes could be irreversible “for centuries to millennia”, while the sea level could rise by up to 1 metre by 2100

Danger of methane:

The concentrations of CH4 ( Methane, the second greenhouse gas after CO2 with a greater warming power) in the atmosphere are at their highest level in 8,00,000 years

Breaking point: unknown

So-called turning points, such as the collapse of ice shelves, thawing of permafrost or transformation of the Amazon into savannah “cannot be excluded”

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There might be some hope

While many of the report’s predictions paint a grim picture of humans’ impact on the planet and the consequences that will have going forward, the IPCC also found that so-called tipping points, like catastrophic ice sheet collapses and the abrupt slowdown of ocean currents, are low likelihood, though they cannot be ruled out.

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