中国气候变化信息网 China Climate Change Info-Net

(2017-07-31)With the first six months of 2017 in the books, average global surface temperatures so far this year are 0.94°C above the 1950–1980 average, according to NASA. That makes 2017 the second-hottest first six calendar months on record, behind only 2016.

That’s remarkable because 2017 hasn’t had the warming influence of an El Ni?o event. El Ni?os bring warm ocean water to the surface, temporarily causing average global surface temperatures to rise. 2016 – including the first six months of the year – was influenced by one of the strongest El Ni?o events on record.

Reality has debunked the ‘warming stopped’ myth
For a long time one of the favorite climate denier myths involved claiming that we hadn’t seen any global surface warming since 1998. That myth has fallen by the wayside since 2014, 2015, and 2016 each broke the global surface temperature records previously set in 2010 and 2005 (which were also both hotter than 1998). Yet the myth persisted for years because 1998 was anomalously hot due to the monster El Ni?o event that year, which meant that global temperatures weren’t much hotter than 1998 until 2014 to today.

Now the first six months of 2017 have been 0.3°C hotter than 1998, despite the former having no El Ni?o warming influence and the latter being amplified by a monster El Ni?o. In 1998, there was also more solar energy reaching Earth than there has been in 2017.

No, Rick Perry, the oceans aren’t to blame
In a recent Senate committee hearing, Trump’s Department of Energy Secretary Rick Perry said that he didn’t believe human carbon pollution is the primary control knob for the Earth’s climate (it is; hence the title of this NASA paper published in the journal Science in 2010), but instead placed most of the blame on “naturally occurring events – the warming and the cooling of our ocean waters.”

That’s a simple hypothesis to test. If global surface temperatures were rising due to an exchange of heat from ocean cycles, then as Perry noted, ocean temperatures would be alternatively warming and cooling. When oceans transferred heat to the surface, their temperatures would cool, and vice-versa. That’s simply not happening – measurements show that the oceans have steadily built up heat:

Instead, every component of the Earth’s climate is warming. Surface air temperatures, lower atmospheric temperatures, ocean temperatures, and sea levels are rising as ice around the globe melts. That’s a key signature not of an internal Earth cycle, but of an external influence – either an increase in incoming energy from the sun, or a decrease in outgoing energy, for example due to an increase in the heat-trapping greenhouse effect. And as we’ve established, there’s actually been a slight decrease in incoming solar energy.

The culprit is quite clearly human carbon pollution. That’s how the first six months of 2017, despite lacking solar or El Ni?o ocean warming, can be hotter than 1998, and 2006, and every year before 2016.

In fact, research has shown that global surface temperatures are already rising about 20 times faster than Earth’s fastest natural climate change, during the transition in and out of ice ages. And unless we take serious action to cut carbon pollution, that rate will rise to perhaps 50 times faster than Earth’s fastest natural climate change.

Climate deniers have recently been shifting to the ‘global warming isn’t bad’ myth. It should go without saying that such rapid climate change is dangerous. Species can only adapt so fast. The IPCC concluded that we’re already approaching the point at which up to 30% of global species are at increasing risk of extinction. If we don’t take action to curb global warming, the IPCC projects that by century’s end, 40% or more of global species could go extinct, as we approach Earth’s sixth mass extinction.

Today’s remarkably hot temperatures, caused by human carbon pollution, are a sign of what’s to come. If we don’t get global warming under control, the consequences will indeed be bad.