As part of a story I recently wrote to describe global warming’s possible economic and climatological ramifications for Houston, I contacted the state’s climatologist, John Nielsen-Gammon, who happens to be a frequent and welcome contributor to this blog.
I found his answer to my question — What is your best guess as to global warming’s effect on Houston’s climate? — worthy enough to be reprinted in its entirety below:
Assuming an increase in global temperatures of 2-3 C (or 4-5 F), which is near the middle of most recent projections, southeast Texas temperature would probably go up a similar amount, maybe a bit more. Texans are adapted to the heat, so there may not be much increase in morbidity due to the summer heat, except for those who can’t afford air conditioning. Summertime outdoor activities (construction, recreation) would be scaled back a bit. In the winter, the reduced severity of cold snaps would lead to greater viability of tropical vegetation and insects.
Impacts on southeast Texas crops and forage would depend upon the change in precipitation, and the overall likely precipitation trend for Texas has not really been pinned down yet. Because of the greater moisture content of the atmosphere, it is nearly certain that flood events would increase in frequency and severity, and it is also likely that droughts would become more severe because the water needs of plants will have increased. Water supplies and ecosystems will be stressed, but population growth will probably have a much larger negative impact than climate change.
Coastal changes are the biggest unknown. Sea level will certainly increase, and reductions in greenhouse gas emissions over the next century would barely make a dent. If that increase remains gradual, as is likely, it will be felt mainly during major events such as hurricanes, when the storm surge is a bit more devastating than it would have been. The combination of increased water usage and sea level rise may have major negative impacts on coastal ecosystems, which in turn would further increase the damage caused by storm surges as the coastal buffer is removed.
The dynamics of the major ice sheets of Greenland and Antarctica are as yet poorly known, and the IPCC’s sea level projections didn’t include the possibility of the collapse of such an ice sheet because the uncertainties were too large to even be able to make a projection. So we have to assume that such a collapse is possible but not likely, with a worst-case scenario of several feet of sea level rise by the end of the century. Such a change would require gradual abandonment of much coastal infrastructure.
Hurricanes receive a lot of attention, but so far no significant increase has been observed in the frequency or strength of landfalling hurricanes, and future increases are likely to be minor. Hurricane impacts will probably increase, though, due to the changes in sea level, precipitation intensity, and population.
This strikes me as probably just about the most level-headed, scientifically grounded forecast you’re likely to get.