Climate (Civ6)

Climate is a new gameplay mechanic which introduces major changes in Civilization VI: Gathering Storm. It represents a major development in the series where climate change and the ways players contribute to it will radically alter the later stages of the game.
== Introduction ==
In previous Civilization games climate was represented implicitly in the different biomes (i.e., the combination of terrain and terrain features) in the world. For example, Plains and Grassland represented a temperate or tropical climate, while Tundra and Snow represented a polar climate, and Desert and features like the Oasis represented a dry climate. Vegetation (forests and jungles) also contributed to the climate representation - for example, jungles are only found in warmer and more humid parts of the world, while forests are found in more temperate and colder parts. This implicit representation finds its ultimate demonstration in the rainforest belts in Civilization VI, emulating real-world extra-warm and humid climates which prevail in the equatorial parts of the world.
Gathering Storm, however, ups the ante and introduces a new system in which climate is represented explicitly, as well as implicitly. This is done in two main ways: by creating special disasters which are linked to particular biomes (for example, Blizzards only occur in the colder parts of the world, while Tornadoes occur only in the warm and temperate parts), and by introducing the climate change system, where players are able to affect the rate of disasters and the melting of the polar caps. The latter may hamper or even cripple entire civilizations late in the game.
== Mechanics of Climate and Climate Change ==
Throughout two-thirds of the game (until the Modern Era or so) climate will only be felt through the disasters occurring in the world. The base rate of these doesn't actually depend on climate itself - it is set for each game at its start by the players themselves. Nevertheless, climate is the main condition controlling the rate of most disasters in the game, just like in real life, and when the climate starts to change due to human (player) activity in the later stages of the game, this will be felt by the increased rate of disasters.
The main factor contributing to climate change is CO2 levels. These are tracked globally and continuously, meaning that each player contributes a certain amount per turn. They may limit their contributions at some point, but this won't alter their previous contributions (at least not until they start running the Carbon Recapture project). CO2 is produced mostly by industry, and more specifically by generation.
CO2 levels are also affected by the global level of deforestation. This means how many Woods, Rainforests, and Marshes have been removed from the map throughout the game.
As CO2 levels increase, the world starts warming up and the climate patterns start to become increasingly unstable; this leads to climate change's first effect: a general increase in the chance for disasters to occur. There is also a greater chance the disasters will be of the most destructive strength (Category-5 Hurricane, 1000 Year Flood, etc.). Finally, after the Antarctic Late Summer Update, a new desertification mechanic comes into play after climate change progresses past Phase IV: all Storms and Droughts now start removing fertility from tiles instead of adding it.
The second effect of climate change is more subtle, but potentially much more destructive and permanent than disasters. This is known as coastal flooding (not to be confused with the Flooding disaster), which may submerge the coastal land tiles throughout the world! And this is how it goes:
* As the global temperature increases due to elevated CO2 levels, the polar ice starts to melt (i.e., Ice tiles will disappear and be replaced by Ocean tiles), which raises the global sea level.
* Coastal lowland tiles will now get threatened by coastal flooding. Each coastal tile has a rating of 1–3, which shows how soon it will get affected by climate change: tiles with a rating of 1 are the lowest ones and will get hit first, while those with a rating of 3 will be affected last.
* As climate change progresses, each several turns all land tiles of the appropriate rating (see the chart below) will either be affected by flooding or get submerged. How often this happens depends on how big global pollution is (that is, how big CO2 generation per turn is).
* Tiles affected by coastal flooding get pillaged (along with whatever happens to be on them, including whole districts with all their buildings). These tiles can still be worked, but they won't enjoy any improvement bonuses. It is still possible to reclaim flooded tiles, but only after the city that owns them builds the Flood Barrier.
* With the continued progress of climate change and the rising of the sea level, flooded tiles will eventually become permanently submerged. This essentially destroys the tiles, along with not only improvements and districts on them, but also any natural features and resources! Submerged tiles can never be recovered, and are replaced by Coast tiles. Note, however, that City Centers cannot be submerged. For more details, see the table under Phases of Climate Change below.
Of course, such disasters will severely limit the use of coasts, especially the coastal flatland so loved by Cultural Victory seekers! You will have to think twice before placing your districts and important improvements on the coastal lowlands; island settling will be particularly dangerous.
Unfortunately, the main factor in climate change - the rise in CO2 levels - is tracked worldwide, meaning that all remaining players contribute to it simultaneously. Even if one conscientious player decides to limit their CO2 emissions, another one may decide to recklessly burn fossil fuels and push the temperature rise. The only way the first player may affect this (short of destroying the second player) is by pursuing Climate Accords in the World Congress. However, the chance to limit climate change is usually minuscule - in games with multiple AI leaders, you're better off preparing for the inevitability of climate change unless you can secure most of the and on the map and prevent your opponents from using it.
=== Phases of Climate Change ===
Climate change will progress through seven different phases of severity as increasing numbers of Climate Change points are earned. Each Climate Change point corresponds to a 0.5° global temperature increase, affecting the world as shown in the table below. In Phase IV and beyond, Storms and Floods will no longer provide fertility. In Phase V and beyond, desertification will start as Storms and Droughts strip off extra yields granted previously by other Storms, with the chances increasing in later phases.
On the World Climate Screen, if you hover your mouse on the Climate Change track, you will see the Climate Change points are calculated by summing up Global Temperature points and Disaster Intensity points. The Disaster Intensity setting has not affected Climate Change since the April 2019 Update, but Firaxis forgot to remove that component, so Climate Change points and Global Temperature points are basically one and the same now.
It is not possible to revert climate change to an earlier phase.
Phase	Points	Sea Level Rise	Coastal Lowland 	Polar Ice Melt	Fertility(Storm or Flood)	Desertification(Storm or Drought)
I 	2 	+0.5 m 	- 	10% 	Yes 	No
II 	3 	+1.0 m 	1 m tiles flooded 	20% 	Yes 	No
III 	4 	+1.5 m 	2 m tiles flooded 	30% 	Yes 	No
IV 	5 	+2.0 m 	1 m tiles submerged	40% 	No 	No
V 	6 	+2.5 m 	3 m tiles flooded 	55% 	No 	Yes
VI 	7 	+3.0 m 	2 m tiles submerged	70% 	No 	Yes
VII 	8 	+3.5 m 	3 m tiles submerged	85% 	No 	Yes
== Pollution details ==
Pollution, which actually causes climate change, is measured mainly via CO2 accumulation. How fast this happens will determine how fast climate change progresses through its phases.
=== Sources of CO2 ===
CO2 contributions are measured in units. There are two main types of sources of CO2; note, however, that each contributes different number of CO2 units to global levels.
* Power Plants. All three types emit CO2, but there are considerable differences in the amounts:
** Coal Power Plants emit the most pollution.
** Oil Power Plants emit less pollution than Coal Power Plants, but more than Nuclear Power Plants.
** Nuclear Power Plants are the most environmentally friendly. They do, however, carry the risk of nuclear accidents.
* Units. All units which consume , , or each turn also produce CO2, but at a reduced rate compared to Power Plants. This can be further reduced by researching Advanced Power Cells.
* Railroad construction. A third, often-overlooked source of CO2 is the construction of the ultimate land infrastructure. Every tile of constructed/upgraded Railroad will consume 1 , which adds pollution, and quite a bit at that. Of course, this is a one-time contribution, and probably cannot compare to long-term contributions related to production, but it must still be taken into account.
=== Pollution formulae ===
The exact pollution amounts are counted on a per-unit of resource consumed basis, rounded down. However, after the Late Antarctic Summer Update units' contributions have been substantially reduced. Now it seems that for means of CO2 contributions each military unit only takes 0.5 resource units. Note that this does not affect the mechanics of resource production flow - there each military unit (except the Giant Death Robot) still takes 1 unit of the relevant resource per turn.
In order for the global temperature to rise by 0.5° (1 Climate Change Point), you will need a different amount of CO2 emissions depending on map size. The CO2 levels displayed in the game do not include the trailing 3 digits for readability.
Map size	Units of CO2 per point	Units of CO2 for Phase VII
Duel 	250,000 	2,000,000
Tiny 	500,000 	4,000,000
Small 	750,000 	6,000,000
Standard	1,000,000 	8,000,000
Large 	1,250,000 	10,000,000
Huge 	1,500,000 	12,000,000
Each type of resource has an assigned number of emitted carbon units per generated, which is 820, 490, and 48 for , , and , respectively. For example, you use 2 units of every turn to generate for 30 turns, resulting in 60 consumed in total, generating 240 units of . In this period, you will discharge 117,600 units of carbon (240 times 490), and the Climate Screen will show the number 117. If the amount of emitted carbon reaches a certain threshold, the global temperature will rise. Remember, each unit of and can generate 4 units of while generates 16 (4 times as efficient), and 's efficiency in generating carbon is so much lower (48 vs. 820 and 490); therefore, when all three types of resources generate the same amount of during the same course of time, is about 68 times cleaner than and 41 times cleaner than .
Since the Climate Screen will show carbon emission after taking away the last 3 digits (divided by 1000 and rounded down to the closest integer), the different fuel types producing CO2 will be displayed on the this Screen as follows:
* : ~3.28 unit of carbon/resource
* : ~1.96 unit of carbon/resource
* : ~0.77 unit of carbon/resource
These numbers are calculated by: (Amount of generated per unit of resource) times (Amount of carbon emitted per unit of ) divided by 1000.
Units that consume one of these types of resources also discharge carbon per turn, but their emissions are equal to only half of Power Plants per unit of resource.
The late game Carbon Recapture project will recover 50,000 units of CO2, while using a Soothsayer charge will add this much. These are more impactful on smaller maps, as the thresholds for Climate Change points vary by map size.
=== Deforestation Level ===
The deforestation level is a percentage of number of features cleared (Marshes, Woods, Rainforests) versus the total number of removable features on the entire map. A high level of deforestation will amplify the amount of CO2 in the atmosphere; conversely, a lower one will result in lower calculated carbon emission.
Deforestation Level	CO2 emission modifier
0-9% 	-20%
10-24% 	0%
25-39% 	+10%
40-49% 	+30%
50%+ 	+50%
== The World Climate Screen ==
All the info about the new climate system may be visualized on the brand new Climate screen, which may be opened from a special button found in the upper left corner of the game screen. The screen is divided in three tabs; by clicking the Overview tab you will see comprehensive info about the current climate situation, as follows:
* The bar in the upper part of the screen shows the current phase of climate change. As temperature rises and the change progresses, it starts filling with red. Mouse over each phase to see the details of what happens in it.
* On the left-hand side you can see:
** The current global level of CO2, adjusted by deforestation level, along with the current leader in emissions (which ignores railroads).
** How much the global temperature has risen since the Ancient Era (mouse over to also see the deforestation level).
** What the current climate game setting is.
* On the right-hand side you may see the relevant chances for each type of disaster. They are based on the game setting, and modified by the climate change described to the left. There is a separate section for each type of disaster; mouse over them to get detailed information on how they affect the world.
* At the bottom of the screen you will see the world sea condition: how much polar ice has been lost, and how much has the sea level risen as a consequence (down to the raw number of tiles which are currently flooded or submerged already).
* In the center you will see info about the latest disaster to have struck the known lands. Details about affected tiles, units and population loss will also appear here.
By clicking on the middle tab you will see more detailed info about contributions to CO2:
* To the left you will see a diagram of CO2 contributions, which may be distinguished by civilization (the diagram will show the distribution of CO2 contributions by all civilizations which ever contributed), or by resource (the diagram shows the division by the three polluting resources). Note that contributions from Railroads are not included in the totals on this side.
* To the right you will see your own civilization's resource contributions to your overall emissions. Underneath the diagram itself you will see how many exactly each resource has contributed - mouse over each one to see the exact contribution in the last turn. This is very useful when determining the exact dynamic of how Power production and Units each contribute to your emissions.
Finally, the right tab of the screen shows a history log of the disasters which have already struck.
File:World Climate overview (Civ6).png|Overview Phase I
File:World Climate overview phase VI (Civ6).png|Overview Phase VI
File:World Climate CO2 levels (Civ6).png|CO2 levels
File:World Climate Event History (Civ6).png|Event history
== Strategy ==
Despite being such a major addition to the game, there's not much strategy involved when dealing with climate and climate change itself. This is due to the fact that climate change is, for the most parts, inevitable. Game mechanics such as advanced units or the new Science Victory ensure that at least several civilizations will start producing CO2 and will keep producing it until climate change occurs. What you need to figure out boils down to two things:
;How to mitigate its effects
Remember, we're not discussing disasters, but the worst permanent effect of climate change: coastal flooding. And there is one very simple method of avoiding (or even fixing) coastal flooding: the Flood Barrier. Simply research the Computers tech ASAP and start building Flood Barriers in all cities which have susceptible tiles in their territory (remember, in cities which have no such tiles, it's not possible to build a Barrier). Once the Flood Barrier is finished in a city, that city not only recovers all flooded tiles on its territory, but is also guaranteed safety from any future coastal flooding events. Note, however, that finishing the Barrier does not recover tiles which were already submerged.
Of course, there's always the chance a city is in such a situation when a Flood Barrier simply cannot be constructed in time! This is particularly true for newly-settled coastal cities which haven't developed their infrastructure enough to build one, or because the climate change process happens too rapidly that the cost of the Flood Barrier scales up constantly. Remember that the cost of the Flood Barrier depends both on the number of tiles the city owns which are in danger of flooding, and the phase of climate change! Each time climate change enters a new phase, the completion of the barrier will be pushed back in time (because its cost will immediately increase). Add to this the possibility of the tiles contributing to production getting flooded (thus reducing overall capacity), and you may easily enter a downward spiral which prevents the city from completing the Barrier in time to save its vulnerable tiles. When you see this happening you should consider removing nearby woods and rainforests or rushing in a few Military Engineers to finish the job.
Or, you can simply avoid settling near coastal areas, especially when you are playing as a civilization who doesn't benefit from coastal settlements, or when you discover that many civilizations in the current game have their preferred victory path to be scientific. In this case, you have to contemplate the level of risk and reward for abandoning the coast. Sometimes, it is much better to take the risk and plan ahead accordingly.
;How much you will personally contribute
This is a much more nuanced question, as it depends a lot on the plan you have in mind for your empire. If your preferred victory path is scientific, or, to a lesser extent, domination, there is not a whole lot of incentives to care about the environment. However, if you are aiming for a Diplomatic Victory, you should think twice before discharging masses of CO2 into the atmosphere. Polluting a lot adds a direct penalty to accumulation, which is the essential currency for winning a Diplomatic Victory. But what's more, polluting hinders your winning of some key scored competitions, which bring Diplomatic Victory points!
So, here you will try to juggle your economic and scientific progress with your CO2 emissions, so as to preserve an optimal balance between the two. You can't avoid some CO2 production (mainly due to production, but also for maintaining an army for defense purposes in the late game); just try to go as "green" as you can. Bet heavily on renewable energy, build as many Hydroelectric Dams as possible, and if you're lucky to have access to , funnel as much of your Power Plant generation through Nuclear Power Plants. And who knows...maybe your going green will actually help slow down climate change after all!
== See also ==
* Climate (change) in other games
Category:Civilization VI: Gathering Storm
Category:Game concepts (Civ6)