Global warming driven by human activity, especially the production of carbon dioxide via the burning of oil and coal. Sunlight easily passes through carbon dioxide. But as sunlight heats up the earth, it creates infrared radiation, which does not pass back through carbon dioxide so easily. The energy from sunlight cannot escape back into space and is trapped.
We also see a somewhat similar effect in greenhouse or cars. The sunlight warms the air, which is prevented from escaping by the glass.
Ominously, the amount of carbon dioxide generated has grown explosively, especially in the last century.
Where all that extra energy from the sun that’s being blocked by the greenhouse gases that we’re putting in the atmosphere where’s that going well it’s going most of it into the ocean if it weren’t going that the planetary surface would have warmed up a lot faster.
Some temperature datasets
Sea surface temperatures (SST)
Marine air temperatures (MAT)
Surface air temperatures (SAT)
Lower troposphere temperature (LT)
How do we take the temperature of the planet we have a number of data sets we have sets like sea surface temperature that are measured by ships that measure the temperature of the water routinely as they plow through the world’s oceans they measure the air temperatures above the ocean marine air temperature we have weather stations all over the world that measure surface air temperature and we have balloons that we send up into the lower troposphere the lower atmosphere and we also have satellite images that look down from above and they can measure the temperature in the lower atmosphere.
All kinds of these some over the land some over the surface some over the oceans and they all basically are telling us the same thing namely that the temperature is going up by all these measures they all agree now we have to be careful we have thousands of thermometers a thermometer on the equator you know measures 98 degrees Fahrenheit, a thermometer in the Arctic measures minus 10 degrees Fahrenheit.
How do we get them all together well a lot statistics goes into that’s one of the reasons we don’t talk about what is the temperature of the earth but what’s the temperature change because the temperature change in Delhi might be comparable to the temperature change in Rajasthan even though the absolute temperatures aren’t the same so we have to do some work on this we have to do some corrections for example.
Temperature Corrections
Instrumentation changes- Instruments change the kind of thermometers we use change sometimes the location there’s a standard height for thermometer it’s about this high if you build a weather station but in some parts the world, they were lower or higher and we have to correct for that.
Sampling techniques
Example: Sea-surface temperatures are a brilliant of example the old days they would throw a bucket overboard haul a bucket up stick a thermometer in it on the deck of the ship and measure it and some of the buckets were made with wood which is a fairly good insulator and some of the buckets were made of canvas, if you bring up the water in a canvas bucket that effect occurs and you get a lower temperature.
Urban heat island effect
One of the most important corrections actually is not that important but in the eyes of skeptics it is this so-called urban heat island effect and the idea is this you built a weather station way back when and two things were happening first of all the city wasn’t nearly as big now cities which generate a lot of energy for heating and transportation and a lot of black surfaces that absorb sunlight.
They tend to be warmer than their surroundings, another effect that’s more subtle is you build a weather station on the outskirts of the city and then the city grows and surrounds the weather station and the temperature goes up and that’s not global warming but it looks like it you measure the temperature over time in that city and it looks like it’s going up well it is going on but not because of global warming.
What’s the cause of this climate change that’s occurring?
Here is the big idea is something called energy balance and you all know about this any system that maintains a constant temperature it sounds complicated in science it will maintain constant temperature if the rate at which energy comes in is equal to the rate at which energy goes out and you all know this because you all pay heating bills in the winter you pay for firewood you don’t pay for your photovoltaic energy that runs your heat pump but you have to put it — provide energy to keep your house warm you pay for oil.
You pay for gas, you pay for whatever you’re paying for what’s going o in your house is this your house is an imperfect keep container it’s got insulation in the walls but nevertheless energy escapes through the walls of your house to the outside and you have to replenish that energy and if you manage to replenish it at the same rate at which it’s leaking out then your house stays at a constant temperature and what your thermostat does to achieve that is to turn the heating system on and off as it needs to if it gets too cold it turns it on gets too hot turns it off again and on average the rate at which your heating system is supplying energy is equal to the rate at which energy goes out and that’s a basic principle of physics.
If you want to maintain a constant temperature in a situation where you are losing energy to the outside or gaining in the summer and you have to take energy out if you’re losing energy to the outside so your surroundings you have got to supply energy to replace the energies look at the same rate and that’s the idea of energy balance.
