Climate change "facts"?

Bob Carter is a geologist and a global warming denier. His recent opinion piece in The Age titled "An inconvenient fallacy" shows him using his own facts. Not being an expert on most of the issues, the Phactor will confine his criticism to just one fact. "Fact 3. Atmospheric carbon dioxide is beneficial. In increasing quantity it causes mild though diminishing warming (useful at a time of a quiet sun and likely near-future planetary cooling) and acts as a valuable plant fertiliser. Extra carbon dioxide helps to shrink the Sahara Desert, green the planet and feed the world. Ergo, carbon dioxide is neither a pollutant nor dangerous, but an environmental benefit."
First of all, does this guy think the Sahara is a desert because of the lack of CO2? OK, well, guess he doesn't garden or have house plants. Probably just a pet rock, and it seldom needs watering.
Next, the stuff about CO2 and plants is sort of OK, but when temperature gets added to the equation things change, and not only won't the Sahara get greener, the Amazonian rainforest might get a lot grassier, i.e., tree death may lead to a grassland savana replacing tropical rain forest. This change-over releases more CO2 because all those woody stems are store houses of CO2 that begin decomposing after the tree dies. This happens all the time, but if there are fewer trees to make wood, more CO2 will be released than taken up. Trees die because the rate of plant respiration continues to go up as temperature goes up, but photosynthetic rate tops out and then begins to decline. This means at higher temps more respiration, less photosynthesis. In one of the few long term studies, tropical tree mortality and average temperatures are negatively correlated; trees just respire themselves to death at higher temperatures. So our geologist is only correct if temperatures remain steady, but average temperatures are positively correlated to atmospheric CO2. Now of course the biologists who have been doing the study, my friends the Clarks, get their salaries and research money from grants, and their data and analyses that get published all have to get by lots of reviewers taking critical looks at their data, ideas, methodology, analyses, knowledge of science, etc., and they've been very successful for nearly 3 decades now. And in just 10 mins the Phactor let the air our of one of Prof. Carter's "facts". So who you gonna go with?