Condensed Summary of Canada's Changing Climate Report

 Here’s what’s happening .. temperatures are climbing, globally

This chart shows temp relative to the 1961-1990 average

So, as you can see, the period from 1850-1900 was well below 1961-90, while 1990-2018 are well above

On net, we are very much well in excess of pre-industrial temperature norms (which is important because the global goals is to keep the planet from being destabilized by keeping temp increase contained to no more than 2C above pre-industrial, and preferrably 1.5C)

Those temp changes are manifesting themselves in other ways

And these other impacts will themselves in turn have a feedback effect on temperatures, creating a vicious circle

So far, that just covers what has happened so far… here’s what we’re looking at for the future

This shows just two possible scenarios, business as usual, what IPCC calls RCP8.5, and something that many would consider a best case, RCP2.6

Note how on the path we are on, which means continued economic growth, which means more consumption of everything, and more use of energy, which so far is predominantly fossil-fuels, CO2 concentrations in the atmosphere will rise not just linearly but exponentially; on the other hand, in order for us to achieve that best-case 2.6 scenario we just mentioned, you can see that rather than having emissions keep growing, we need to have them quickly plateau and head to zero, and, in fact, below zero (meaning we utilize new technologies to extract more carbon from the atmosphere than we put in)

Some people think, hey, we live in Canada, its cold, no big deal if it gets warmer

Except, for one thing, temperatures are rising further and faster here in Canada than globally, and especially up north in the Arctic

Canada is warming at twice the global rate, and the Arctic at thrice the global rate.. that is hugely destabilizing

So while it might seem okay in southern Ontario, we need to worry about those feedback effects we mentioned earlier… as the Arctic warms, not only are polar bears and other wildlife at risk, but less snow and ice means less albedo effect, and warming tundra means melting permafrost, which releases methane, a very potent GhG into the atmosphere, both from land and from the seabeds, which will cause a huge feedback effect, and greatly accentuate warming, to the extent that it can spiral out of control (Hothouse Earth scenario)

Here’s what climate models, as of the 2013 IPCC report, say will happen to global temperatures as we continue to emit emissions

2 things to note about that:

• these are the projected global avg changes, and, as we just saw, Canada will warm twice as much and the Arctic thrice as much
• global climate change models have improved in the last 6 years, and the latest estimates suggest the climate is even more sensitive than we previously thought, so temperatures will rise even further and faster than is shown here

Note that the majority of climate scientists consider it unlikely that we will fall below the low ranges of the above estimates, but remain concerned that we could exceed the high ranges (which already allow for 25% chance of being exceeded).. but could be worse due to feedback effects, tipping points and irreversibilities in the climate system

If we see these types of temperature changes in the 8.5 scenario, imagine the impacts related to:

·         hot and cold extremes

o    i.e. greater weather variability than we’ve experienced this year

·         extreme weather events,

o    causing flooding on the one hand, and

o    droughts on the other

·         and related knock-on effects on

o    groundwater and freshwater availability

o    our agricultural sector, our growing season, etc.

·         wildfires

·         ocean temperature and ocean acidification

o    and impacts on fisheries

·         sea level rise

o    storm surges for our coastal infrastructure / cities

Uncertainties prevail! Keep in mind that most estimates we see from models are based on chances / estimates

There are still significant risks of things being worse than we currently judge (and over the last 30 years, that has typically been the case, that outcomes have been generally worse than earlier anticipated)

Which raises the question of whether we want to accept a 50% or 25% or even 10% chance of temperatures getting even higher