June shatters records; 2015 start is warmest on record

While Minnesota's temperatures numbers are closer to average so far in 2015, global temperatures are on pace to smash the warmest year on record so far, according to the National Oceanic and Atmospheric Administration's latest State of the Climate report.

It's not just that global temperatures are breaking records. It's the magnitude of the records that has climate watchers doing a triple take.

Here's some more perspective on the recent run of record warmth from Capital Weather Gang's Jason Samenow.

NOAA, NASA and the Japan Meteorological Agency (JMA) have each reported the global warmth of June 2015 matched or exceeded any previous June in historical records. Given the extremely warm months preceding June, 2015 is on track to have its warmest year on record, following the the record warm year of 2014.

Every month in 2015 so far has ranked among the top four warmest, and June joined March and May as having warmth unsurpassed in records dating back to 1880, NOAA said Monday morning.

June 2015 shattered the previous record for warmest June set just last year (2014) by 0.22 degrees (0.12 Celsius). “This was … the fourth highest monthly departure from average for any month on record,” NOAA’s report said. Both land and ocean temperatures set record highs for the month.

The first six months of 2015 marked the warmest first half of the year on record for the globe, 1.53 degrees (0.85 Celsius) above the 20th century average, 0.16 degrees (0.09 Celsius) ahead of 2010, which had the next warmest opening to a year.

Climate Central notes that 13 of the 15 warmest years on record have all occurred since 2000. The odds of that happening? One in 27 million.

Also contributing to June’s heat was the overall warming of the atmosphere thanks to the excess heat trapped by accumulating greenhouse gases. That background heat has tilted the odds toward record global temperatures.

A Climate Central analysis conducted after 2014 became the warmest year on record showed that 13 of the 15 warmest years have occurred since 2000 and that the odds of that happening randomly without the boost of global warming was 1 in 27 million.

Some of those top warm years were when La Niña — the cool counterpart to El Niño — was in place, and were warmer than past El Niño years.

Scientists can’t say for sure what will happening in the remaining six months of 2015, but right now the evidence suggests El Niño will last until spring and will likely strengthen in the coming months, making it a good bet that the globe will see more top warm months.

“We do know that as El Niños strengthen, they do tend to cause global temperatures to rise,” Blunden said. “The first half of 2015 is already 0.16°F warmer than the previous record for the first half of 2010, which happens to be when we had the last El Niño. If this current El Niño does continue to strengthen, it seems almost certain that 2015 will beat out 2014 as the warmest year on record.”

Hansen paper opening eyes

Another eye opening piece of climate news this week comes from a new paper by climate scientist James Hansen. In the paper, Hansen and his colleagues argues that the pace of melt in Greenland and Antarctic ice sheets is grossly underestimated.

He projects a more sudden and dramatic ice loss and corresponding sea level rise in the next 50 to 200 years when compared to the more conservative and linear projections from IPCC.

The paper is opening eyes, but has garnered criticism as being too speculative by many climate experts. Alarmist? Or alarmingly good science?

Slate's Eric Holthaus wrote this.

In what may prove to be a turning point for political action on climate change, a breathtaking new study casts extreme doubt about the near-term stability of global sea levels.

The study—written by James Hansen, NASA’s former lead climate scientist, and 16 co-authors, many of whom are considered among the top in their fields—concludes that glaciers in Greenland and Antarctica will melt 10 times faster than previous consensus estimates, resulting in sea level rise of at least 10 feet in as little as 50 years. The study, which has not yet been peer-reviewed, brings new importance to a feedback loop in the ocean near Antarctica that results in cooler freshwater from melting glaciers forcing warmer, saltier water underneath the ice sheets, speeding up the melting rate. Hansen, who is known for being alarmist and also right, acknowledges that his study implies change far beyond previous consensus estimates. In a conference call with reporters, he said he hoped the new findings would be “substantially more persuasive than anything previously published.” I certainly find them to be.

The Washington Post's Chris Mooney has more reaction.

So is this abrupt climate change scenario really something we should take seriously? We received reactions to the paper from a number of top climate researchers — and their responses varied:

Michael Mann, a climate researcher at Penn State University who reviewed the paper at the Post’s request, commented by email that “their case is most compelling when it comes to the matter of West Antarctic ice sheet collapse and the substantial sea level rise that would result, potentially on a timescale as short as a century or two.” But Mann was more skeptical of other aspects of the work.

“Their climate model scenario wherein Greenland and Antarctic meltwater caused by warming poles, leads to a near total shutdown of ocean heat transport to higher latitudes, cooling most of the globe (particularly the extratropics), seems rather far-fetched to me,” Mann said. Nonetheless, Mann said, “Whether or not all of the specifics of the study prove to be correct, the authors have initiated an absolutely critical discussion.”

Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research, an expert on sea level rise and the oceans’ overturning circulation, commented by email that “I agree that 2 C warming is dangerous and will very likely commit our home planet to meters of sea-level rise.” Rahmstorf had not yet had time to review the full Hansen paper Monday, so his comment was strictly about the danger of major sea level rise, not the other scenarios outlined in the study.

Rahmstorf has previously suggested that among past periods featuring higher seas, the Eemian may not be the best analogy for where the planet is headed, given that changes at that time were driven by planetary orbital cycles, rather than carbon dioxide emissions.

Kevin Trenberth, an influential climate researcher at the National Center for Atmospheric Research in Boulder, Colorado, was critical of the paper, calling it “provocative and intriguing but rife with speculation and ‘what if’ scenarios.” Trenberth objected in particular to the climate modeling scenarios used to study freshwater injection as ice sheets melt. “These experiments introduce a lot of very cold fresh water in various places, and then they see what happens,” he wrote by email. “The question is how relevant these are to the real world and what is happening as global warming progresses?   They do not seem at all realistic to me.”

“There are way too many assumptions and extrapolations for anything here to be taken seriously other than to promote further studies,” Trenberth wrote.

Richard Alley, a glaciologist at Penn State University and an expert on the planet’s ice sheets, said that the study by Hansen and his colleagues was likely to prompt a lot of thought. “Many parts of the new paper are likely to stimulate much technical discussion and further research in our community, as we try to weave together the deep-time and recent history to provide useful projections for the future,” he said by email.

“This new paper is not ‘the answer,'” Alley continued. “Particularly, replacing the simple assumptions about doubling times of ice loss with physically based insights is a major focus of our field, but is not yet done and not likely to be ready really quickly.” Alley acknowledged that the IPCC’s sea level rise estimate “is well on the optimistic low-rise side of the possible outcomes,” and added that “the estimates in the new paper of freshening, and discussion of stabilization of the southern ocean and influences on precipitation, are interesting and important.”

Michael Oppenheimer, Albert G. Milbank Professor of Geosciences and International Affairs in the Woodrow Wilson School at Princeton University, commented by email that “If we cook the planet long enough at about two degrees warming, there is likely to be a staggering amount of sea level rise.  Key questions are when would greenhouse-gas emissions lock in this sea level rise and how fast would it happen? The latter point is critical to understanding whether and how we would be able to deal with such a threat.

“The paper takes a stab at answering the ‘how soon?’ question but we remain largely in the dark.  Giving the state of uncertainty and the high risk, humanity better get its collective foot off the accelerator.”

Thus, in light of these comments, it seems safe to say that the intellectual process of digesting the new paper has already begun. And while some researchers are already calling into question some of the more novel scenarios involving meltwater freshening, ocean circulations and storms, the work’s concerns about major sea level rise from melting ice sheets appear hard for scientists to rule out.