Graham Lloyd is back with a story headlined “Climate link to Sandy invalid” (Google the title if you want to read it). As we’ve come to expect from The Australian the headline is contradicted by the story, with both scientists quoted agreeing that sea level rise caused by global warming had worsened the flooding from Sandy. Lloyd writes (all links in quotes added by me):
In a statement on the disaster that hit North America on Monday, the federal government-sponsored Climate Commission said “all the evidence suggests that climate change exacerbated the severity of Hurricane Sandy“. …
Professor England said increased humidity, higher sea levels and warmer sea surface temperatures were all contributing to the severity of storms.
All of which is true, so how does Lloyd make a claim that the “Climate Commission has misrepresented data”?
The commission quoted data from the National Oceanic and Atmospheric Administration that “the temperature of the surface waters from which Sandy drew energy were three to five degrees warmer than average”.
However, senior NOAA climate scientist Martin Hoerling said the higher sea-surface temperatures quoted by the Climate Commission were not significant in relation to Sandy.
Dr Hoerling told US public radio in the aftermath of Sandy that ocean temperatures adjacent to the US eastern seaboard had been running several degrees higher than normal.
But he said the unusually warm waters were in areas where the background temperature was relatively cool. “So adding a few degrees Fahrenheit at that cool water temperature doesn’t matter too much for the intensity of a hurricane,” Dr Hoerling said.
In other words, it does matter, but it it’s not as important as unusually warm tropical water as Matthew England explained to Lloyd:
“So the climate change signal in Sandy is largely due to sea-level rise, the increased humidity in the world’s atmosphere, and the tropical ocean temperature anomalies. The temperatures up near New York, while still a factor in the storm, are less of a factor than the above three changes.”
Or, as Lloyd spins it, “Professor England conceded the sea-surface temperature highlighted in the Climate Commission document was not significant.” Well, no, that’s not what he “conceded”.
Completely missing from Lloyd’s story was this, from the Climate Commission:
Warmer oceans now and into the future are likely to influence the intensity of cyclones. A recent study summarised this as follows:
“We find that warm years in general were more active in all cyclone size ranges than cold years. The largest cyclones are most affected by warmer conditions and we detect a statistically significant trend in the frequency of large surge events (roughly corresponding to tropical storm size) since 1923. In particular, we estimate that Katrina-and magnitude events have been twice as frequent in warm years compared with cold years (P < 0.02)”.
Warmer temperatures make for stronger surges and hence likely made Sandy worse. Which I guess is why it didn’t appear in Lloyd’s story. Tamino has more on the study.