Download Are the measurements accurate enough to reliably show changes in

Are the measurements accurate enough to reliably show
changes in the level of CO2 in the atmosphere?
Yes! The oscilla>ons in the level of CO superposed on
the overall increase are due to the leaves falling in
Autumn and coming out in Spring!
Is there really a correla>on between CO2 content and temperature?
Varia>ons of temperature and CO2 content track each other closely, both for recent data (leF) and
data for many thousands of years obtained from ice
cores (right).
Are ice-­‐core measurements reliable enough to be sure
they give a good idea of past CO2 content in the
atmosphere?
Yes! During the decades when we have both ice-­‐core And direct measurements, they agree very well.
So what do the CO2 varia>ons tell us?
The current level of CO2 in the atmosphere is higher
than it has been over the previous 400,000 years. This
cannot be due to a natural cycle! Is there any evidence of actual warming?
Many more glaciers in the world are retrea>ng (mel>ng)
than advancing, and the Arc>c, Antarc>c and Greenland
ice caps are all losing ice mass.
A significant rise in sea level (due to thermal expansion)
has been measured, and the rate at which this rise is
occurring is accelera>ng.
Although it is difficult to demonstrate that any par>-­‐
cular storm is associated with climate change, the
frequency of excep>onal weather events is rising.
Whether or not a par>cular storm is “due to climate
change,” the effects of climate change can increase the
damage it does.
For example, sea level rises by about 1cm for every
drop in air pressure of 1 millibar. Thus, the increases in
sea level due to the low pressure of a storm will be
added to the sea level increase due to climate change.
A given storm has more poten>al energy and
destruc>ve poten>al since waves fall from a greater
height and reach higher up the coastline.
But do direct measurements provide any evidence
that the temperature is actually rising?
Yes! It has now been conclusively demonstrated that
there has been a rise in temperature by 0.85° since
1880, when reliable temperature measurements
started being made.
How likely is it that the temperature rise is due to
human ac>vity – aren’t there other possible causes?
Aerosols reduce T through
reflec>on of incident light
Incident solar energy
fluctuates with solar cycle
and randomly
It is extremely likely (sta>s>cally > 95%) that human
ac>vity has been the dominant cause of the observed
temperature rise since the mid-­‐20th century.
The total temperature rise is determined by the total
cumula>ve CO2 emissions. In order to keep total
temperature rise below 2°, we should aim to keep
total CO2 emissions below 790 Gt.
“There are approximately two decades leF to achieve
the large scale decarbonisa>on necessary to avoid
dangerous climate change.”
— Prof. John Sweeney, NUI-­‐Maynooth
 The CO2 content in the atmosphere is increasing due
to human ac>vity, and the expected rise in temperature
has also been measured.
 There is abundant evidence already that this rise in T
is affec>ng the Earth’s climate and weather pakerns.
 Big changes in how we get our energy
(decarbonisa>on) are going to be required over the next
couple of decades. This is not in the future, this is now!
 This >me scale coincides with the start and early
stages of your careers – providing great opportuni>es to
be part of the solu>on needed, both scien>fically and
poli>cally!