The evidence is such that the cause of the increase of one degree centigrade in average earth surface temperatures over the past 250 years is over 90% certain to be the doubling of the concentration of CO2 in the lower atmosphere. However, there is a global carbon cycle, explained in every first year class in Ecology, that must be understood in order to know how to lower CO2 concentrations.
Living plants consume CO2 and water and exude oxygen. Decomposers consume oxygen and dead plants to produce CO2 and water. These effects are, generally speaking, in balance. However, if plant matter does not decompose, because it becomes fossilized, the carbon in it gets buried in the ground, becoming, coal, oil, and natural gas, and lowering atmospheric concentrations of CO2. Back in the so-called Carboniferous Era, about 500 million years ago, more or less, Earth was significantly warmer, plant life was more lush, sea level was higher, large shallow inland seas existed on most continents, and large amounts of dead plant matter were fossilized. Eventually, under colder conditions, perhaps due to the removal of the CO2 from the air, permanent ice formed, sea levels dropped, shallow seas disappeared, less plant material was buried unrotted, and, by early human prehistory, only the occasional bog or marsh collected significant amounts of undecayed hydrocarbons.
In the beginning of human civilization, only currently produced hydrocarbons, wood and animal wastes, were used as fuel, so burning and decomposition were roughly in balance with carbon fixation by plant growth. However, about 400 years ago, rocks that burned were discovered and developed as sources of fuel, and mankind started returning to the atmosphere the CO2 that was fixed during the Carboniferous. Since 1750, the CO2 concentration has been doubled, although it is still lower than it was during the early Carboniferous. That doubling has increased average earth surface temperatures about one degree Centigrade, still cooler than what it was during the early Carboniferous.
Removing all trees will not remove CO2 from the atmosphere, it will add CO2 to the atmosphere. We need, not fewer trees, but more of them, and less burning of fossil fuels. There were no ice caps or glaciers during the Carboniferous, sea levels were much higher, and dry land was much scarcer. We barely have enough dry land to support our civilization at present - we cannot afford to lose any of it. More than one third of the world's population lives less than twenty meters above sea level - if we do not prevent the ice from melting, all those people will have to move uphill, somewhere, and much of the cropland that grows their food will be inundated by the sea. The cure for global warming is increased carbon fixation and decreased combustion of fossil fuels. Up to now, deforestation has had net negative effects in this regard.