Not in history; hottest on record, which is very different.
Right-wingers who play that particular rhetorical game don't tend to be very consistent with their anal approach. For example, if one of their fellow right-wingers says that Obama has the worst ______ in history, you'll never seem them pop up and say "not in history, just on record.... that particular stat has only been collected since the 1960s." But, when it comes to climate, they're quick to draw the distinction, despite a temperature record going back 136 years.
Still, your point is fair. We only know this was the hottest August in 136 years. However, we have decent climate reconstructions going back for thousands of years before we had good direct temperature measurements, and although they don't fine-tune the data to the point where we can say anything definitive on a month-to-month basis, when we look at multi-year averages, we see that we're running swiftly away from the multi-year averages going back for thousands of years. Here's what a 1000-year reconstruction looks like:
Note, that stops in 2004, and nearly every year since 2004 has been hotter than 2004, including 2015 being 0.33 degrees Celsius higher on that anomaly chart (it would bust right out the top of the chart).
As far as climate change being here, of course it is. Can you point to a time when there was no climate change?
You're being willfully ignorant. The claim here isn't just that climate is changing. Of course it is. It always has and it always will. The claim is that it's changing at a pace that's very likely unprecedented in the history of civilization, as a result of anthropogenic ghgs, and that the unprecedented pace of change will likely continue if we don't get our emissions under control.
If it helps, think of it in medical terms. Say that you've been hitting the bottle really hard for several years, and your health is going to crap at a rapid pace. You've put on a lot of weight, your strength has declined, your memory is getting worse and worse, your blood pressure is up, etc. Your doctor (and nearly every doctor) would recommend you cut way back on your drinking. But what if you were a self-indulgent [Unwelcome language removed] who wanted to convince yourself there was no price to be paid for not changing? Well, in that case you could mumble incoherently, demanding people point to some time when bodies aren't changing. You'd be right, of course, that throughout people's lives their bodies change, and that everybody declines a bit with age. But if you took comfort from that and took it as permission to keep up the behavior that is causing incredibly rapid decline in your own case, that would be a huge mistake.
Climate change is also occurring on Mars, by the way.
If the Earth had an orbit like that of Mars, and no big oceans to serve as heat sinks, and we were experiencing changes similar to Mars, the vast majority of experts wouldn't be united in saying human activities are causing more of our change. But our orbit is only a fifth as eccentric as Mars's, and we do have oceans, and we have no evidence of past changes, based on orbit eccentricity, anywhere close to as rapid as the changes we're experiencing now.
https://www.skepticalscience.com/global-warming-on-mars.htm
