Echt, dat die vraag nog steeds iedere keer weer gesteld moet worden, dat is nog wel het aller-ergst. Dat blokkeert fatsoenljk dialoog naar oplossingen of vooruitgang, en dat impliceert twijfel die er al tientallen jaren niet meer is over hoe en waarom de aarde opwarmt;
Earth's surface is collecting more than 4 Hiroshima atomic bombs worth of heat every second. Energy going in, and no longer going back out into space, thanks to the growing blanket of heat-trapping greenhouse gases, mainly CO2, H2O and CH4.
When I was born there were ~300 billion (yes, 9 zeros) more trees than there are now. And still, at today's rate; for every new born human about 100 trees disappear from earth, and are not replenished. Those are even low estimates, according to most who've done counts ~27 million trees disappear from earth/day. The lack of sufficient tree-cover alone, globally, should be responsible for at least 2 degrees Celsius warming at surface level over land, for the past 50 years. The fact that we haven't observed that 2 degrees rise (yet) is most likely thanks to added pollution (i.e. global dimming), oceanic intake of heat and lowering solar output over that same time-span.
Tree cover is an enormous influence on temperature and moisture. Plus very sensitive to becoming feedback loops in changing climates; Trees can't migrate at the observed speeds of change, each migratory process is either coincidence, man-made or by evolutionary drivers. Trees go down sooner when soil is drier, when storms are stronger, when extreme low/high T make them less resistant to disease, older trees now die younger reducing leaf-count, and there's a growing nr of wildfires. CO2 intake is highly impacted by all of them, and they are -obviously- feedback loops.