Even with warming, a 'fact' would be a data point at a particular time and location, assuming your sensor was correctly calibrated. You have to look at millions of data points across the entire globe for decades to get a sense of the current warming rate (which could be negative, flat, or positive). You have to do complicated statistics on all those data points to get a warming rate, and you'll have error bars on that, and the end result is not a 'fact' so much as a bounded estimate (+0.1 C / decade +/- 10% is plausible for the average surface temperature change averaged over the entire planet).
We can't even say with real certainty that 2100 will be warmer than today, as a supervolcano, asteroid impact, or global nuclear war could reverse the trend.