However many years we have. Whether it's 20, 30, 40, the data does not find any warming.
The data you're citing is based on ground level temperature probes, not satellites.
I'm not posting that image to cite the data, I'm posting the image to show how you're cherrypicking data to deny the truth of what's happening. You can also click the link I posted, which notes: "But if you take the entire record, then the trend is 0.123 degrees Celsius per decade."
But, since the image is of ground temperature probes, they clearly show warming. You have to consider all the data - and all of the data sources we have show that the warming is happening.
I honestly don't understand why you (or anyone) is questioning whether the warming is actually happening. It clearly is. The only reason to doubt the instrument record is some kind of denial or motivated reasoning.
You don't have to consider data sources that have known inaccuracies. Satellite imaging is much more accurate and has found bupkis. Ground temp probe data is biased to the Heat Island Effect and will effectively be over-sampled. Sure, it's good data to inform state, city, and federal governments when planning for city expansion and making sure enough greenery is around to mitigate it, but as for informing global policy on carbon emissions, no, just no.
The warming is not clearly happening. One pole is melting while the other is expanding. The Troposphere is cooling. The oceans have not gotten one iota warmer. The only thing getting warmer is air near cities, and as the Sun becomes less and less active over the next few thousand years, even that won't be a problem. Heck if we enter another mini ice age as we cyclically should in the next hundred years, those hot and bothered cities will become refuges for the freezing suburbans and rural dwellers.
Satellite imaging is not
more accurate when measuring either surface or atmospheric temperatures. From that same Washington Post article I posted:
Mears and Benjamin Santer, a climate scientist at Lawrence Livermore National Laboratory, recently co-authored a strong critique of Cruz’s “Data or Dogma” hearing. “Satellites are not a thermometer in space, they’re not making direct measurements of atmospheric temperature, they’re measuring the microwave emissions from oxygen molecules,” Santer said. He cites numerous types of uncertainty associated with satellite temperature data and numerous corrections to it required — such as due to satellites’ orbital drifts — making the entire endeavor a “tough job.”
“There’s over a dozen satellites that you need to string together and each of them have calibration and drift issues that need to be dealt with,” added Gavin Schmidt, director of the Goddard Institute for Space Studies at NASA. “If there’s an issue with any particular satellite or any particular calibration it affects all the temperatures, so it’s much easier to have systematic issues that affect the whole record.”
Likewise, the idea that warming is only found in cities from urban heat islands is also untrue. We have temperature records from non-urban surface locations. We have them from weather balloons. We have them from ocean buoys.
Every comprehensive analysis of all the data shows the warming is clearly happening. Even increased snow/ice at one of the poles is actually consistent with warmer temperatures - you don't get snow accumulation when it's too cold!