Tuesday, July 19, 2016

First Half-of-Year Records in Temperature and Arctic Sea Ice Extent

Source: http://svs.gsfc.nasa.gov/12305

On a NASA teleconference, Gavin Schmidt, Director of GISS, said this record is "Not solely due to El Nino event." GISS calculates about 40% of record is due to El Nino and 60% due to other factors, including very, very strong Arctic warming."

Other things he said:

"The trend is very clear, and it's due to greenhouse gases."

"2017 is not going to be as warm as 2016." [due to starting the year in a neutral or La Nina condition]

"If 2016 sets a record, it will be the third record year in a row, which is unprecedented in our record." (99% chance 2016 sets a record.)

"May have some cooling in coming years, but the trends are going to continue, obviously."

"Paris thresholds are long-term equilibrium temperatures changes.....We are dancing with those lower [Paris] targets."

"No statistically robust that there is a strong acceleration" of warming. [Natural noise too hard to disaggregate. Natural trends pretty stable....] "It's premature to talk about acceleration in the 21st century."

For Arctic sea ice:


David in Cal said...

There's no doubt that global warming has been continuing. But, I am curious about the reason for looking at Arctic sea ice without also looking at Antarctic sea ice. The Antarctic sea ice anomaly is close to the 1981- 2010 average.


David Appell said...

Because the Antarctic is a very different place than the Arctic. And it's so isolated it doesn't have the repercussions that Arctic melting does.

Also, Arctic sea ice is melting 10 times faster than the Antarctic is gaining ice:


and that doesn't include the big decline in Antarctic sea ice this year.

Harry Twinotter said...

My guess it is going to take a long time for the Antarctic to warm up enough to affect it's sea ice extent. It is becoming clear that the Arctic has crossed some sort of threshold; it stands to reason the Antarctic will take longer to cross the same threshold.

David Appell said...

Plus, much of the Antarctic continent is at altitude -- it tops out at 4.9 km (16,100 ft).

OnymousGuy said...

David, your last comment needs to be emphasized. Warming of the Southern Ocean results in penetration of warmer waters below the ice sheets extending from the continental land mass into the ocean, thinning these sheets and decreasing ice volume and the stability of the ice sheet. Warming of the Southern Ocean also results in greater water vapor pressure, which then results in increased precipitation in the Antarctic highlands. So accretion of land-based ice and depletion of ice sheets extending into the ocean are both results of global warming. And yes, the amount of ice surrounding Antarctica is a small fraction of Arctic sea ice. The absence of a land mass in the Arctic Ocean makes a very significant difference.

David in Cal said...

Not that it proves anything, but Antarctic sea ice extent is now slightly greater than Arctic sea ice extent. Back in 1979, Arctic sea ice extent used to average around 12.5 million km^2. It's now down to around 11 million km^2. Antarctic sea ice extent has pretty consistently averaged around 12 million km^2. See http://www.climate4you.com/images/NSIDC%20GlobalArcticAntarctic%20SeaIceArea.gif


Allan Barr said...

If you take into account slumping of ice into the ocean I believe you will discover why Antarctica appears to be staying relatively stable.