evidence: Raw data shows more global warming [...] You can see that adjustments to the data have relatively little effect on global temperatures after 1950. The rate of warming between 1950 and 2016 in the adjusted data is just under 10% faster than the raw data, and only 4% faster since the start of the modern warming period in 1970. The adjustments that have a big impact on the surface temperature record all occur before 1950. Here, past temperatures are adjusted up – significantly reducing the warming over the past century. Over the full 1880-2016 period, the adjusted data actually warms more than 20% slower than the raw data. The large adjustments before 1950 are due almost entirely to changes in the way ships measured temperatures (more on that later).