In Which I Compare Your Sunday Roast to Our Planet Earth

Growing up as I did, I learned a fair bit about cooking.  I don’t mind cooking, it’s not my favorite activity and cleaning is way down on the list, so I don’t cook that much.

Every Sunday, while I was a young teenager, we had a roast (or ham) for Sunday lunch.  Granddad would put the roast in the oven before we left for church and set the timer.  We’d come back home to a smell that still makes my mouth water.

Unfortunately, sometimes, the pastor ran over.  Everyone would grumble as the chances for getting first in line at Luby’s diminished.  But we all sat and waited.

Granddad’s oven had a timer, so why, after one of the pastor’s rare marathons, did the roast come out burned to a crisp?

If you ever watch Alton Brown on the Food Channel, he often talks about something called carry-over heat or carry-over cooking.

OK, you’ve got a roast in a 350°F oven for two hours, why do you take it out when the internal temperature is 145°F (if you like it really rare) or 165°F for non-beef meats (including hamburger)?

We all know that we have to kill the bacteria in the food and 165 will do that, but meat is a pretty good insulator.  There’s lots of water and proteins that can absorb a lot of heat energy before changing temperature.  So, the outside 1/16th of an inch of the roast might well be 350°F, but deep inside, it’s just barely 165°F.

But 165°F is a good temperature to eat roast at, everything is cooked appropriately.  But what happens as that roast sits in a 350°F oven for another hour?

Well, the oven is very well insulated.  It has to be or we’d burn the crud out of ourselves when we tried to open it up and the kids would burn their noses watching the cake rise.  So the oven retains that heat, even when the heat source is shut off.

Heat energy flows from higher temperatures to lower temperatures.  Over time, the entire oven (and everything in it) will slowly reach the same temperature, even allowing for a small amount in heat leakage to outside of the oven.

So, that Sunday roast of ours was still sitting in an oven and slowly increasing in temperature.  With the unpleasant result of being tough and dry.

Even if you take that roast out of the oven, the outside is still hotter than the inside and some of the heat is going to continue to increase the internal temp.

That is carry-over heat or carry-over cooking.  Ideally (according to Alton Brown), you take the roast out of the oven when the internal temp is 145°F.  The carry-over heat will bring the roast to the perfect temp of 165°F in a little while.  If you do this correctly, then you get the perfect roast.

Now we get to some more trickery from the Food Channel (and maybe some things you’ve done).  If you are cooking soft boiled eggs, then you want to cook them for a specific amount of time in boiling water and then you want them to stop cooking.

So, you take the eggs (or veggies or whatever) off the stove, you put them into cold water (or cool water for the eggs) to stop the cooking process.  You want to bring the external temperature low enough so that carry-over cooking doesn’t overcook the eggs (or veggies).

Now, how does all that apply to the planet Earth.

Well, we’re in an oven.  However, this oven doesn’t turn off.  Some heat does leak from the oven, but we’re putting a blanket around the oven and slowly causing less heat to escape, increasing the temperature of the oven.

The carry-over heat will be bad.

We’re already having record breaking temperatures, record breaking floods, record breaking  droughts, record breaking hurricanes and tornadoes.

The current global temperature increase since pre-industrial times is 0.76°C.  That’s all.  Even if we stopped all greenhouse gas emissions tomorrow, we are committed to global warming carry-over of at least another 0.7°C.  That’s a total of 1.4°C.  Think about how much fun the weather will be then.

We’re carrying over a lot of greenhouse gases that we can’t easily get rid of.

If you want realistic scenarios (here), then we’re looking at a minimum (if everything runs perfectly and we start working on this now) of a 1.1°C (over what we already have).  If you want the pessimistic side, then we’re talking an increase of 6.4°C (over what we already have).

So, we’ve increased the global temperature by .76°C now and we have the ability to take it another 6 full degrees.

Please keep in mind that these changes occur over the next 89 years (by 2100).  Yes, we could see that 6 degree increase in temperature within our lifetimes, certainly our children will see it.

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