By chance or luck or fate after I made my post on the CO2 thread yesterday about the crossing of the tipping point this morning I got a headline in my email news server.
Oops, Scientists May Have Miscalculated Our Global Warming Timeline
The sloppy news article then led me to the actual science report published in Nature.com.
300 years of sclerosponge thermometry shows global warming has exceeded 1.5 °C
Abstract
Anthropogenic emissions drive global-scale warming yet the temperature increase relative to pre-industrial levels is uncertain. Using 300 years of ocean mixed-layer temperature records preserved in sclerosponge carbonate skeletons, we demonstrate that industrial-era warming began in the mid-1860s, more than 80 years earlier than instrumental sea surface temperature records. The Sr/Ca palaeothermometer was calibrated against ‘modern’ (post-1963) highly correlated (R2 = 0.91) instrumental records of global sea surface temperatures, with the pre-industrial defined by nearly constant (<±0.1 °C) temperatures from 1700 to the early 1860s. Increasing ocean and land-air temperatures overlap until the late twentieth century, when the land began warming at nearly twice the rate of the surface oceans. Hotter land temperatures, together with the earlier onset of industrial-era warming, indicate that global warming was already 1.7 ± 0.1 °C above pre-industrial levels by 2020. Our result is 0.5 °C higher than IPCC estimates, with 2 °C global warming projected by the late 2020s, nearly two decades earlier than expected.
For those science inclined readers the full article is available here,
Nature.
The upshot of the article lays out the scientific evidence that we had already warmed between 1.6 and 1.8 C four years ago in 2020 and we are rapidly approaching the 2.0 C threshold that was considered a major tipping point before the infamous Paris Climate agreement of December 2015 reset the level to 1.5 C.
To be perfectly clear I said at the time and I continue to say the 1.5 C goal was nothing but empty political posturing. Given what has taken place in the eight years since that goal was named I maintain I was proven correct. Not only has no government anywhere done anything effective to reduce carbon emissions, Germany in the intervening years closed five perfectly safe and functional zero carbon nuclear power plants and China has maintained a building rate of more than one new Coal fired power station per week for the last eight years. In plain language we didn't just fail to reduce carbon emissions, major governments have adopted strategies that worked to greatly increase carbon emissions instead.
As I pointed out in the CO2 thread yesterday, only taking into account the CO2 and CH4 forcing and not counting all the other greenhouse gasses in the atmosphere already we are at the equivalent of 540 ppmv CO2 today with an annual increase over 2 ppmv fresh CO2 added every year.
Climate models have shown and paleoclimate records have repeatedly confirmed over multiple data sets using multiple different proxy methods that when Earth has had 540 ppmv CO2 in the past world average temperatures were 3 C above the 1850 baseline temperature. What is even more significant in the paleoclimate record is this 3 C difference while measured globally is true the effects were not global at all.
Instead what scientists have shown, repeatedly, is that the climate system is extremely regional. That 3 C global increase is actually a 1 C increase in the southern hemisphere which is dominated by ocean and a 5 C increase in the northern hemisphere which is where most of the continental land mass of the planet is located. 67 percent of the land on Earth is in the north with the remaining 33 percent in the south. Put another way over 80 percent of the surface south of the equator is water while in the north the figure is 60 percent water more or less.
That disparity in ocean surface area has a profound impact on regional climate, especially if you take into account that a full continent of that southern land is in Antarctica under a 3 km thick ice sheet. Ice sheets and permafrost are enormous heat sinks that serve to absorb energy in the summer season and release that energy in the winter. Open ocean also has this same effect on a lesser scale. In other words because Antarctica is massive and frozen over deeply with ice the disparity between climate impacts on the North and South is even greater than just the percentage difference in sea surface implies. Roughly half of South America, 40 percent of Africa and all of Australia is not much land compared to Asia, North Africa, Europe, North America and half of South America.
The Arctic Ocean while currently still frozen has a much thinner ice cover than it had in 2004 just two decades ago. Someday soon the remaining Arctic ice cover will thaw in summer which will allow the Arctic Ocean to absorb massively more energy in late summer. The biggest northern heats sinks are the Greenland Ice Sheet and the permafrost zone that covers much of Canada, Siberia and Alaska. Unfortunately the Permafrost zone is already collapsing and rapidly retreating north which is eliminating another of those three heat sinks. This leaves just the Greenland Ice Sheet as the last bastion heat sink in the Northern Hemisphere and since 2012 there have been a number of melting events indicating its stability is not as great as we once thought. In fact we know that 125,000 ybp the Greenland Ice Sheet was just half its current size because in the last Interglacial thaw before the current one about half of it melted and world sea levels were 7 meters higher than today.
So welcome to the world on the edge of 2 C greater temperature and prepare yourselves for the 5 C warmer world in the north because once the permafrost melts and the Arctic Ocean turns blue things will change far faster than most believe is possible.
