So as I’m sure a lot of you have seen there are estimates on
how the Earth’s climate has changed for many thousands of years. All of them
are suggesting that we are currently experiencing an upward trend which isn’t
great news but that is not what this post is going to be focusing on. Humans
have only really been measuring temperatures for the last few hundred years, so
the question is where did these reading come from?
Well there are so many different methods of measurin
g
climate that I’m going to do split it into a couple of different posts.
To start with we are going to look into the current methods
of measuring temperature in really time. Now in most cases this means that an
item known as a Stevenson shelter is used. It is possible that you’ve even seen
one of these, possibly out the window while waiting at an airport. A Stevenson
shelter is a standardised white box which lifts a thermometer away from the
heat being radiated from the ground whilst being well shaded and receiving a
good amount of air flow across a standard thermometer. There are problems with Stevenson shelters
however, for instance until recently very few of these boxes were found in the
southern hemisphere, this has leads to historic data being unevenly distributed
across the global. Another issue is the physical location of each shelter, as to
get reliable long term data ideally shelters should remain in the same spot. Unfortunately
increased urbanisation creating both heat island and the need for space has meant
that a lot of shelters are being moved which can also disrupt data. 
It’s not only air temperature which records are kept on, sea
surface temperatures have also been monitored for several hundred years, but
the methods of doing so have been changing. At first a wooden bucket was
lowered of the side of a ship and the temperature was gained from this small sample. This wooden bucket was then replaced with a canvas bucket in the late
19th century which caused a spike in temperatures due to the
insulating properties of canvas and wood. This practise was again changed
during World War 2 as the water sample was taken from the engine inlet valve
instead of the side of the ship so again a second jump in temperature readings
was seen. The lack of consistencies within the measuring protocol has meant
they require a standardisation so as a consistent record can be created. There
are also further problems with measuring sea surface temperature which are similar
to Stevenson shelters in the fact that in the beginning ships were usually
confined closer to shore the majority of the time, so overall coverage of readings
are at points an issue. In recent years a modern method for monitoring sea
surface temperature has been developed which uses satellite imaging to provide
nearly complete coverage sea across the world. Yet again these measurements
need to be standardised to continue temperature records. These satellites can
also be used to measure sea level rises.
The final modern method of measuring deep water temperatures
are Agro floats. These are autonomous robots which are capable of descending
two thousand meters under the oceans and taking multiple different temperatures
reading over the course of ten days before it resurfaces and uploads the data
to a series of satellites. These floats are important as changes in deep sea
temperatures could seriously disrupt their productivity and so have a knock on
effect on shallower waters and terrestrial environments. However like ever kind
of measurements there are limitations, for instances there have been problems
with the floats becoming trapped under ice when taking reading close to the
poles and so the spread of data is disrupted again.
So these are just a few modern methods which are utilised to
measure
the changes in the Earth’s climate to allow us to see how human
activities and natural variations are effecting global temperatures. However as
I said earlier this is just the tip of the iceberg, we currently have accurate global
temperature records for many thousands of year so how was these achieved?
The answer is through the use of proxy measurements.
Stay tuned for the second of these two posts which will look into exactly how proxy
measurements are used in historical records.
Thanks for reading!
Check out this link which shows a remarkable amount of
progress in the UK when it comes to shopping bags.
Check out this video from Redbull
No comments:
Post a Comment