When the streets are icy, don't slip and fall on the evidence of climate change. It's underfoot all around you.
An amazing NOAA video shows how CO2 levels have changed up and down over the past 800,000 years, with a significant spike recorded since the Industrial Age began. This is the evidence from which you can readily judge whether humans have contributed to the increase in greenhouse gas emissions (GHE). Don't get distracted by the busy-looking screenshot--after all, it's a history of the world in fewer than three minutes.
Now the video starts to go back in time, modestly at first. The green line shows another labeled data set going back to 1958.
[1:27 to 1:41 on video]
Now we enter the realm of firm data from nature's time capsule--that slippery ice. If you look at any chunk of ice today you'll notice small bubbles in it. Those bubbles are a product of today's atmosphere. If you were to scrape off the ice from atop a glacier and get down to the ice made a few years ago, the bubbles in the ice at that layer are from the atmosphere of that recent year. Dig deeper, say, to the ice of 50 years ago, and you get bubbles from the atmosphere of 50 years ago. See NASA introduction to ice cores.
The video's graph (in orange) shows CO2 levels that overlap the recent data and continue back in time to the pre-industrial age, with CO2 around 278 ppm. The time span shown on the x-axis is in years Before Common Era (BCE), going back 2,000 years. Already you can see there is a significant spike in the latter centuries.
[1:41 to 2:08 on video]
We dig deeper into the past by digging deeper into the ice. Notice that the scale on the bottom of the graph soon shifts to kyBCE--that's thousands of years before the common era. We're going way back now, through epochs of ice ages. Some people like to dismiss climate science because we've admittedly had ice ages and warming periods in the past, as if that negates the evidence. The graph shows the evidence for you to interpret.
The time scale is compressed until it spans 800,000 years of ups and downs. Realize that temperature levels (as expressed by ice age and non-ice age) correlate directly with CO2 levels--they are nearly in lockstep. Sure, over time we've had temps go up and down with variations in natural CO2 levels, but look at that right edge of the graph. That last-minute spike, the so-called pump handle, is a harbinger of ensuing temperatures.
[2:08 to 2:38 on video]
Video credits show the respected institutions that contributed to the data presented in the video. Take time to realize this typifies climate science in that the evidence represents the consensus of the scientific community. Are there outliers who dismiss this? Of course. But the preponderance of evidence--what you yourself can interpret--indicates CO2 levels are skyrocketing in the era of modern industrial man.