Post on 31-Dec-2015
description
• We developed a method to estimate the impact of land-use change (including urbanization and agriculture) on surface temperatures
• We compare the surface observations with the NCEP 50 year Reanalysis, which is insensitive to land-use change
• Obtained that the impact of land-use changes is comparable in magnitude to that of greenhouse gases.
Impact of urbanization and land-use on climate change
Eugenia Kalnay and Ming Cai(Nature, 2003)
Issues:
• The two most important anthropogenic activities that impact climate:
1. increase of greenhouse gases
2. changes in land use
• They both tend to produce surface warming so that their impacts are very difficult to separate.
• The impacts of changes in land use have been regarded as “noise”, compared to impacts of increase of greenhouse gases.
1950’s:Tob-Tan=0.0
1960’s:Tob-Tan=0.61
1970’s:Tob-Tan=0.60
1980’s:Tob-Tan=0.80
1990’s:Tob-Tan=1.40
Example: Baltimore City, MD
With time, the observations (in red) become warmer than the reanalysis (in blue).We attribute the difference in the trends, at least partially, to urbanization and other land-use changes.
OBS
REANAL
OBS - REANAL
and attribute the difference to land-use changes
We do it for each station
Land-use changes over the US explain:
• About 40% of the observed increase in Tmin
• Most of the observed decrease in Tmax
• Half of the decrease in diurnal temperature range (-0.14 out of –0.28 C/decade)