According to many sources (like climate central) atmospheric carbon dioxide (co2) has passed the 400ppm (parts per million) mark as of March 2015 or so. The level was just over 300ppm when I was born in 1950, meaning the rate of increase in my lifetime (thanks to our global carbon-based economy) is unprecedented.
graph from climate central article
You can see from the chart how quickly humans have increased the co2 in the air recently. A key characteristic of co2 is that it takes centuries to scrub from the environment.
Clearly this intensifies the urgency with which we need to develop a non-carbon based economy. It also means that amelioration -- basically changing our lifestyles and even moving en masse in some cases -- is going to become more important, as it's unlikely that we'll be able to wind the clock back completely on this.
On a more macabre note, an important effect of climate change, together with other environmental issues, is that the world will unlikely be able to support the population expected over the next decades (9B or so). All those people unable to survive locally aren't going to sit down and die quietly. This means migration, and desperate conflicts.
Sorry, kids. Brace yourselves.