Impacts of Climate Changeand their mitigation

Bill MenkeOctober 6, 2005

Most of this material drawn fromIPCC REPORTS

I’ve saved a copy at my web site …www.ldeo.columbia.edu/users/menke/data/ipcc/index.html

You should read the technical summaries … at least !

Note that global temperatureis predicted to increase by as

much as little as1 deg C

or as much as5 deg C

in the next centurywith most models in the

2-4 deg Crange

Current Temperature Distribution

Note that 5 deg C is one color band

Note that 5 deg C is one color band

Impact 1 –Spread ofMalaria

India – deaths in 1947: 800,1000 deaths in 1986: 1000

At what temperatures is malariapresenthard to control ?

Impact 2 –Reduction inArctic Ecosystems

Tundra

Tundra

What temperatureBoundary controlsThe southern extentOf Tundra ?

Impact 3 – Reductionin River Runoff

Hydrologic Cycle: Note land precipitation of 108,000 km3

And that 58% evaporates, with the rest, 46,000 km3,flowing in rivers. But only about 5000 km3 are usable foragriculture

Typical land, about 1 meter (40”) of precipitation, 42% (17”) is runoff

Now increase temperature 3 deg C (5.3 F),runoff decreases to 14.5”, a drop of 15 percent

3 deg C

Model that takes into account overall climate changes alsoPredicts regions (e.g. in red) where runoff is down by 15%

Food From WaterCaloric need: 2000 kCal per person per dayGrain: 4000 kCal per kg6 Billion People on earthWater needed to grow that grain: 1 m3 per kg

Putting it all together, agriculture requires

1100 km3 of water per yearas long as we’re all vegetarians

So to feed a world of vegetarians requiresabout

1/5 of the available runoff

a 15% drop in runoff is a very big deal