Getting a better handle on the definitions of and differences between "global warming" and "climate change" will help us understand why the threat caused by continued warming of the planet is so serious.
While greenhouse gases are an essential component of a livable planet - they're what keep Earth from being a lifeless ball of ice - humans are causing greenhouse gas levels to increase so quickly that it's causing the average global temperature to rise much faster than it would naturally. This warming is predicted to lead to a variety of negative effects, including:
1) Melting (and possible disappearance) of glaciers and mountain snow caps that feed the world's rivers and supply a large portion of the fresh water used for drinking and irrigation.
2) A rise in sea levels due to the melting of the land-based ice sheets in Greenland and Antarctica, with many islands and coastal areas ending up more exposed to storm damage or even underwater.
3) Increasingly costly "bad weather" events such as heat waves, droughts, floods, and severe storms.
4) Lowered agricultural productivity due to less favorable weather conditions, less available irrigation water, increased heat stress to plants, and an increase in pest activity due to warmer temperatures.
5) Increases in vector-borne infectious diseases like malaria and Lyme Disease.
6) Large numbers of extinctions of higher-level species due to their inability to adapt to rapidly changing climate and habitat conditions.
The first two of these effects are mostly related to increasing average temperatures. Items 3-6 are related to heat too, but also playing a role are non-temperature factors - i.e. "climate-change factors."
Climate change is about much more than how warm or cool our temperatures are. Whereas "global warming" refers to increasing global temperatures, "climate change" refers to regional conditions. Climate is defined by a number of factors, including:
1) Average regional temperature as well as day/night temperature patterns and seasonal temperature patterns.
3) Precipitation (average amounts and seasonal patterns).
4) Average amount of sunshine and level of cloudiness.
5) Air pressure and winds.
6) Storm events (type, average number per year, and seasonal patterns).
To a great extent, this is what we think of as "weather." Indeed, weather patterns are predicted to change in response to global warming:
1) Some areas will become drier, some will become wetter.
2) Many areas will experience an increase in severe weather events like killer heat waves, hurricanes, flood-level rains, and hail storms.
It's tempting to think that all of these changes to the world's climate regions will average out over time and geography and things will be fine. In fact, colder climates like Canada may even see improved agricultural yields as their seasonal temperatures rise. But overall, humanity has made a huge investment in "things as they are now, where they are now."
Gone are the days of millennia ago when an unfavorable change in climate might cause a village to pack up their relatively few belongings and move to a better area. We have massive societal and industrial infrastructure in place, and it cannot be easily moved. Climate-change effects will generally not be geographically escapable in the timeframe over which they happen, at least not for the majority of humans and species.