It’s probably good to start with the scientific consensus. Ninety-seven percent or more of peer-reviewed and actively publishing climate scientist agree that climate change that has occurred over the past hundred years is likely attributable to human activities. You can find information to support almost any claim out there but the overwhelming majority of reputable scientists working in this field are in agreement that climate change is very real. One important indicator scientists point to is the accumulation of heat in our oceans. While temperatures on land fluctuate in response to natural forces (such as volcanic eruptions), ocean temperatures are far slower to respond to such factors. This is very useful because it allows us to separate human caused climate change from other possible factors affecting climate. Ocean temperatures have been rising by over .1 of a degree each decade for the past fifty years. These changes have not fluctuated or deviated from a steady increase. This is just one piece of evidence among many, but it’s compelling because the world’s oceans are naturally resistant to short-term, temporary fluctuations.

Evidence for natural climate change - plenty. For man-made - NONE; read on.

The “evidence” for man-made climate change comes from Global Climate Models (GCM).

In 2007 Al Gore famously said “The science is settled.” Now - if the science is settled, why would there be any modelling going on now? But there are more than 50 GCMs running around the world. And you would expect them to produce identical results. They all differ.

If you take the output from models from 10 years ago and compare projections with reality – they are wrong and they run hot.

Nobody knows how the climate works. The modellers think they know how CO2 will affect the climate – thus that “knowledge” is built in to the models..

Here are a few of many excellent articles that describe how GCMs work, and their shortcomings

http://www.drroyspencer.com/2009/07/how-do-climate-models-work/

https://wattsupwiththat.com/2014/10/16/a-simple-truth-computer-climate-models-cannot-work/

https://scied.ucar.edu/longcontent/climate-modeling

Briefly: GCMs are based on distorted “Cubes” derived from horizontal and vertical grids, typically 100km wide and 1km deep. Each cube has properties such as the amounts of each atmospheric gas, wind speed, air pressure etc. The model runs forward in time in steps of 30 minutes or more (any reduction in size and time makes run times impractcal).

The model needs to be checked against reality. A date in the past – say 50 years ago – is chosen and ALL CUBES ARE INITIALISED with starting properties. Now – how much of this is known – for the whole planet and up to the top of the atmosphere – from 50 years ago? How do you initialise the 5th cube up1000 kms east of New York in the Atlantic?

Well, using clever techniques (guesses) the initialisation is done. The model then runs and produces results that don’t match with what happened in the 50 years. That’s EXPECTED because there are factors that are not understood – an important one being clouds. For these factors the modellers provide parameters that are adjusted until the model produces something near to reality.

The conclusion is that the model and the parameter settings must be correct. The model is then run into the future to project what will happen. This is where, years later, it is clear that all run hot. See many places, but here for example https://judithcurry.com/2015/12/17/climate-models-versus-climate-reality/

You see, the problem is that nobody knows how the climate works.

Over the past one and a half centuries, there are tons of evidence that indicate climate change is happening. The changes include the rise of temperatures on land, changes in key dates when rivers and lake freeze, the melting of solar ice caps, a reduction in the number of glaciers, and plants having an extended period of growth. The heat stored in oceans, which usually takes a lot of time to change has been increasing over the past 50 years. We have also seen changes in the patterns of rainfall which has resulted to either intense rain or droughts or even flooding. Climate change has also affected some animals and plants biologically. There has been a shift in the ranges where some animal and plant species can be found and mistiming of events such as bird migration and egg laying in some species. These pointers indicate that climate change is real and it is happening on our watch.