Is road construction with all of the asphalt an influence on global warming ?

Question

Is road construction with all of the asphalt an influence on global warming ?

Answer 1

There is a theory regarding this, known as the "Heat-Island Effect" -- not just asphalt on the roads, which is dark and causes local heat buildups, but forest denuded for farmland and the roofs of buildings.  All of these things provide dark surfaces where heat builds.

Definitely a local warming effect, which may also cause an effect globally.

Answer 2

The short answer is yes, but not because it makes the actual average global temperature any noticeably warmer.  It actually affects our perception of the global temperature.

The Urban Heat Island effect can raise the average temperature around a city by several °C.  Because most of our population lives in cities, this can strongly influence the public perception of Global Warming, as people see more days without snow, or several "heat waves" in summer.

More than that, most of our temperature collecting instruments are located in and around major cities in industrialized countries, where the Heat Island effect is most substantial.  This leads to an upwards skew in the annual average global temperature.  Currently, the size of the skew is unknown, but could be larger than the 0.5°C increase recorded over the last 100 years.  Of course, this could mean that after accounting for the Heat Island effect, we may find global temperatures have actually dropped, which is well within the realm of possibility.

http://www.epa.gov/hiri/about/measuremen...

In terms of CO2 production, building roads can ease congestion, which improves efficiency, and reduces CO2 emissions (as well as oil usage).  Of course, if all your highway department does is remake the same old congested road, then all they did was add to pollution.

Answer 3

It's not the laying of asphalt itself, but the fuel traffic will burn.

Answer 4

Not on a global scale.  It influences a small percentage of land.  Most of the earth is covered by the oceans.

It can affect temperatures stations in cities, so NASA makes some small corrections to remove this "urban heat island effect":

"Also the GISS ranking of years is commonly different than that obtained from the NOAA or British analyses. This is expected, as there are significant differences in the methods. For example, the urban warming that we estimate (and remove) is larger than that used by the other groups (as discussed in 2001 Hansen et al. reference above)."

http://www.columbia.edu/~jeh1/distro_rea...

With that influence removed, the trends still show significant warming:

http://www.columbia.edu/~jeh1/mailings/2...

Answer 5

Well, asphalt is a very good absorber of sunlight, meaning it does indeed contribute to the Urban Heat Island effect. However, the UHI has a minimal effect on overall global warming. A much bigger influence is, as has been mentioned, the rise in fuel-run vehicles running along those asphalt roads.