Since this comes up a lot, a quick run though of the testable, falsifiable, science that supports a human cause of recent trends in global mean temperature.

First off, we start with the observations:
1) spectra from space showing absorption of upward infra-red radiation from the Earth& #39;s surface.
2) Measurements from around the world showing increases in CO2, CH4, CFCs, N2O.
3) In situ & space based observations of land use change

We develop theories.
1) Radiative-transfer (e.g. Manabe and Wetherald, 1967)
2) Energy-balance models (Budyko 1961 and many subsequent papers)
3) GCMs (Phillips 1956, Hansen et al 1983, CMIP etc.)

We make falsifiable predictions. Here are just a few:
1967: increasing CO2 will cause the stratosphere to cool
1981: increasing CO2 will cause warming at surface to be detectable by 1990s
1988: warming from increasing GHGs will lead to increases in ocean heat content

1991: Eruption of Pinatubo will lead to ~2-3 yrs of cooling
2001: Increases in GHGs will be detectable in space-based spectra
2004: Increases in GHGs will lead to continued warming at ~0.18ºC/decade.

We test the predictions:
Stratospheric cooling? https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark">
Detectable warming? https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark">
OHC increase?https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark">
Pinatubo-related cooling?https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark">
Space-based changed in IR absorption? https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark">
post-2004 continued warming?https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark">

With this validated physics, we can estimate contributions to the longer term trends. https://www.bloomberg.com/graphics/2015-whats-warming-the-world/">https://www.bloomberg.com/graphics/...

This too is of course falsifiable. If one could find a model system that matches all of the previously successful predictions in hindcasts, and gives a different attribution, we could test that. [Note this does not (yet) exist, but let& #39;s keep an open mind].

We can also look at the testable, falsifiable, theories that were tested, and failed.
Solar forcing? Fails the strat cooling test.https://abs.twimg.com/emoji/v2/... draggable="false" alt="❌" title="Cross mark" aria-label="Emoji: Cross mark">
Ocean circulation change? Fails the OHC increase test https://abs.twimg.com/emoji/v2/... draggable="false" alt="❌" title="Cross mark" aria-label="Emoji: Cross mark">
Orbital forcing? Fails on multiple levels https://abs.twimg.com/emoji/v2/... draggable="false" alt="❌" title="Cross mark" aria-label="Emoji: Cross mark">

If you have a theory that you don& #39;t think has been falsified, or you think you can falsify the mainstream conclusions, that& #39;s great! We can test that too! (But lots of people have tried this already so expect there to be an answer already).

PS. Actually, it& #39;s even a bit harder. Not only would you need to find a theory that does as well as the current theory, but you& #39;d also need to show why the current theory isn& #39;t operative.