As an area of study, economic growth is generally distinguished from development economics. The former is primarily the study of how rich countries can advance their economies. The latter is the study of how poor countries can catch up with rich ones.
As economic growth is measured as the annual percent change of gross domestic product (GDP), it has all the advantages and drawbacks of that measure.
The short-run variation of economic growth is termed the business cycle, and almost all economies experience periodical recessions. The cycle can be a misnomer as the fluctuations are not always regular. Explaining these fluctuations is one of the main focuses of macroeconomics. There are different schools of thought as to the causes of recessions but some consensus- see Keynesianism, Monetarism, New classical economics and New Keynesian economics. Oil shocks, war and harvest failure are obvious causes of recession. Short-run variation in growth has generally dampened in higher income countries since the early 90s and this has been attributed, in part, to better macroeconomic management.
The long-run path of economic growth is one of the central questions of economics; in spite of the problems of measurement, an increase in GDP of a country is generally taken as an increase in the standard of living of its inhabitants. Over long periods of time, even small rates of annual growth can have large effects through compounding (see exponential growth). A growth rate of 2.5% per annum will lead to a doubling of GDP within 28 years, whilst a growth rate of 8% per annum (experienced by some Four Asian Tigers) will lead to a doubling of GDP within 9 years. This exponential characteristic can exacerbate differences across nations. For example, the difference in the annual growth from country A to country B will multiply up over the years. A growth rate of 5% seems similar to 3%, but over two decades, the first economy would have grown by 165%, the second only by 80%.
In the early 20th century, it became the policy of most nations to encourage growth of this kind. To do this required enacting policies, and being able to measure the results of those policies. This gave rise to the importance of econometrics, or the field of creating measurements for underlying conditions. Terms such as "unemployment rate", "Gross Domestic Product" and "rate of inflation" are part of the measuring of the changes in an economy.
In mainstream economics, the purpose of government policy is to encourage economic activity without encouraging the rise in the general level of prices (in other words, increase GDP without creating inflation). This combination is seen as, at the macro-scale (see macroeconomics) to be indicative of an increasing stock of capital. The argument runs that if more money is changing hands, but the prices of individual goods are relatively stable, then it is proof that there is more productive capacity, and therefore more capital, because it is capital that is allowing more to be made at a lower cost per unit. See Economies of scale, Inflation, Hyperinflation, Price, Supply and demand.
than GDP. GDP still remains by far the most often-used measure, especially since, all else equal, a rise in real GDP is correlated with an increase in the availability of jobs, which are necessary to most individuals' survival.
In the early modern period, some people in Western European nations developed the idea that economies could "grow", that is, produce a greater economic surplus which could be expended on something other than mere subsistence. This surplus could then be used for consumption, warfare, or civic and religious projects. The previous view was that only increasing either population or tax rates could generate more surplus money for the Crown or country.
Now it is generally recognized that economic growth also corresponds to a process of continual rapid replacement and reorganization of human activities facilitated by investment motivated to maximize returns. This exponential evolution of our self-organized life-support and cultural systems is remarkably creative and flexible, but highly unpredictable in many ways. Since science still has no good way of modeling complex self-organizing systems, various efforts to model the long term evolution of economies have produced few useful results.
During much of the "Mercantilist" period, growth was seen as involving an increase in the total amount of specie, that is circulating medium such as silver and gold, under the control of the state. This "Bullionist" theory led to policies to force trade through a particular state, the acquisition of colonies to supply cheaper raw materials which could then be manufactured and sold.
Later, such trade policies were justified instead simply in terms of promoting domestic trade and industry. The post-Bullionist insight that it was the increasing capability of manufacturing which led to policies in the 1700s to encourage manufacturing in itself, and the formula of importing raw materials and exporting finished goods. Under this system high tariffs were erected to allow manufacturers to establish "factories". Local markets would then pay the fixed costs of capital growth, and then allow them to export abroad, undercutting the prices of manufactured goods elsewhere. Once competition from abroad was removed, prices could then be increased to recoup the costs of establishing the business.
Under this theory of growth, the road to increased national wealth was to grant monopolies, which would give an incentive for an individual to exploit a market or resource, confident that he would make all of the profits when all other extra-national competitors were driven out of business. The "Dutch East India company" and the "British East India company" were examples of such state-granted trade monopolies.
In this period the view was that growth was gained through "advantageous" trade in which specie would flow in to the country, but to trade with other nations on equal terms was disadvantageous. It should be stressed that Mercantilism was not simply a matter of restricting trade. Within a country, it often meant breaking down trade barriers, building new roads, and abolishing local toll booths, all of which expanded markets. This corresponded to the centralization of power in the hands of the Crown (or "Absolutism"). This process helped produce the modern nation-state in Western Europe.
Internationally, Mercantilism led to a contradiction: growth was gained through trade, but to trade with other nations on equal terms was disadvantageous. This – along with the rise of nation-states – encouraged several major wars.
David Ricardo would then argue that trade was a benefit to a country, because if one could buy a good more cheaply from abroad, it meant that there was more profitable work to be done here. This theory of "comparative advantage" would be the central basis for arguments in favor of free trade as an essential component of growth.
Income per capita was essentially flat until the industrial revolution. This period of time is called the Malthusian period, since it was governed by the principles explained by Thomas Malthus in his "Essay on the Principle of Population." In essence, Malthus said that any growth in the economy would translate into a growth in population. Thus, although aggregate income could increase, income per capita was bound to stay roughly constant. The mainstream theory of economic growth states that with the industrial revolution and advancements in medicine, life expectation increased, infant mortality decreased, and the payoff to receiving an education was higher. Thus, parents began to place more value on the quality of their children and not on the quantity. This led to a drop in the fertility rates of most industrialized nations. This is known as the breakdown of the Malthusian regime. With income increasing faster than population growth, industrialised economies substantially increased their incomes per capita in the next centuries.
Many economists view entrepreneurship as having a major influence on a society's rate of technological progress and thus economic growth. Joseph Schumpeter was a key figure in understanding the influence of entrepreneurs on technological progress. In Schumpeter's Capitalism, Socialism and Democracy, published in 1942, an entrepreneur is a person who is willing and able to convert a new idea or invention into a successful innovation. Entrepreneurship forces "creative destruction" across markets and industries, simultaneously creating new products and business models. In this way, creative destruction is largely responsible for the dynamism of industries and long-run economic growth. Former Federal Reserve chairman Alan Greenspan has described the influence of creative destruction on economic growth as follows: "Capitalism expands wealth primarily through creative destruction—the process by which the cash flow from obsolescent, low-return capital is invested in high-return, cutting-edge technologies."
The notion of growth as increased stocks of capital goods (means of production) was codified as the Solow-Swan Growth Model, which involved a series of equations which showed the relationship between labor-time, capital goods, output, and investment. In this modern view, the role of technological change became crucial, even more important than the accumulation of capital. This model, developed by Robert Solow and Trevor Swan in the 1950s, was the first attempt to model long-run growth analytically. This model assumes that countries use their resources efficiently and that there are diminishing returns to capital and labor increases. From these two premises, the neo-classical model makes three important predictions. First, increasing capital relative to labor creates economic growth, since people can be more productive given more capital. Second, poor countries with less capital per person will grow faster because each investment in capital will produce a higher return than rich countries with ample capital. Third, because of diminishing returns to capital, economies will eventually reach a point at which no new increase in capital will create economic growth. This point is called a "steady state".
The model also notes that countries can overcome this steady state and continue growing by inventing new technology. In the long run, output per capita depends on the rate of saving, but the rate of output growth should be equal for any saving rate. In this model, the process by which countries continue growing despite the diminishing returns is "exogenous" and represents the creation of new technology that allows production with fewer resources. Technology improves, the steady state level of capital increases, and the country invests and grows. The data does not support some of this model's predictions, in particular, that all countries grow at the same rate in the long run, or that poorer countries should grow faster until they reach their steady state. Also, the data suggests the world has slowly increased its rate of growth.
Unsatisfied with Solow's explanation, economists worked to "endogenize" technology in the 1980s. They developed the endogenous growth theory that includes a mathematical explanation of technological advancement. This model also incorporated a new concept of human capital, the skills and knowledge that make workers productive. Unlike physical capital, human capital has increasing rates of return. Therefore, overall there are constant returns to capital, and economies never reach a steady state. Growth does not slow as capital accumulates, but the rate of growth depends on the types of capital a country invests in. Research done in this area has focused on what increases human capital (e.g. education) or technological change (e.g. innovation).
Analysis of recent economies' success shows a close correlation between growth and climate. It is possible that there is absolutely no actual mechanism between the two, and the relation may be spurious. In early human history, economic as well as cultural development was concentrated in warmer parts of the world, like Egypt.
According to Acemoglu, Johnson and Robinson, the positive correlation between high income and cold climate is a by-product of history. Former colonies have inherited corrupt governments and geo-political boundaries (set by the colonizers) that are not properly placed regarding the geographical locations of different ethnic groups; this creates internal disputes and conflicts. Also, these authors contend that the egalitarian societies that emerged in colonies without solid native populations, and which could be exploited by individual farmers led to better property rights and incentives for long-term investment than those where native population was large, and together with the tropical climate, colonizers were led to plunder and ruin, and to create exploitative institutions, a situation which did not foster growth or private property rights. Colonies in temperate climate zones as Australia and USA did not inherit exploitative governments since Europeans were able to inhabit these territories and set up governments that mirrored those in Europe. It is important to note that Sachs, among others, do not believe this to be the case.
Other intellectuals report that the narrow view of economic growth, combined with globalization, is creating a scenario where we could see a systemic collapse of our planet's natural resources.
There are concerns with the environmental and ecological effects of economic growth, especially relating to growth in mining, forestry, agricultural and industrial activities. Many researchers feel these sustained environmental effects can have an effect on the whole ecosystem. They claim the accumulated effects on the ecosystem put a theoretical limit on growth of these activities. Some draw on archaeology to cite examples of cultures they claim have disappeared because they grew beyond the ability of their ecosystems to support them. Since it is axiomatic that it is impossible to grow indefinitely within a finite system, economic growth as it is now conceived must, of logical necessity, fail at some time, just as the growth of bacteria in a Petri dish must come to an end. The problem lies in the throughput of materials (mine-manufacture-use-dispose) in the economy as it is presently set up. In making the transition to a more stable and sustainable economic system, growth in the green sector of the economy will occur naturally.
The rate or type of economic growth may have important consequences for the environment (the climate and natural capital of ecologies). Concerns about possible negative effects of growth on the environment and society led some to advocate lower levels of growth, from which comes the idea of uneconomic growth, and Green parties which argue that economies are part of a global society and a global ecology and cannot outstrip their natural growth without damaging them.
The Austrian School argue that the concept of "growth" or the creation and acquisition of more goods and services is dependent upon the relative desires of the individual. Someone may prefer having more leisure time to acquiring more goods and services. Also, they claim that the notion of growth implies the need for a "central planner" within an economy. To Austrian economists, such an ideal is antithetical to the concept of a free market economy, without the presence of governmental intervention. As such, Austrian economists believe that the individual should determine how much "growth" s/he desires.
Most growth in economic activity necessitates some growth in consumption of resources - for instance, it is impossible to produce goods without resource and energy inputs, and it is impossible to have the economy running without the further input of energy to transport people and goods. Steady growth is, by its nature, an exponential function. A quantity that grows according to an exponential function exhibits a doubling in size at a regular time interval (called the doubling time). If the rate of consumption of a non-renewable resource is growing steadily (for instance, 5% per year), then that rate will double regularly. At 5% growth per year, in approximately 14 years the consumption rate will have doubled. After another 14 years the rate will have quadrupled. After a century of 5% annual growth, the resource will be consumed at a rate 130 times the original rate.
Those more optimistic about the environmental impacts of growth believe that, although localized environmental effects may occur, large scale ecological effects are minor. The optimists claim that if these global-scale ecological effects exist, human ingenuity will find ways of adapting to them.
Canadian scientist, David Suzuki stated in the 1990s that ecologies can only sustain typically about 1.5-3% new growth per year, and thus any requirement for greater returns from agriculture or forestry will necessarily cannibalize the natural capital of soil or forest. Some think this argument can be applied even to more developed economies.
Mainstream economists would argue that economies are driven by new technology and ongoing improvements in efficiency — for instance, we have faster computers today than a year ago, but not necessarily computers requiring more natural resources to build. Also, physical limits may be very large if considering all the minerals in the planet Earth or all possible resources from space colonization, such as solar power satellites, asteroid mining, or a Dyson sphere. The book Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets is one example of such arguments. However, depletion and declining production from old resources can sometimes occur before new resources are ready to replace them. This is, in part, the logical basis of the Peak Oil phenomenon.
The predicted rate of economic growth has important implications for climate change policy with regards to a reduction in economic growth due to a reduction in greenhouse gas emissions, versus the economic threat of climate change in the next 100 years.
Some insurance industry analysts claim that the rate of increase in property destruction due to the effects of climate change are projected to exceed the world's total economic output by 2065.
The Stern Review, published by the United Kingdom Government in 2006, concluded that an investment of 1% of GDP per annum would be sufficient to avoid the worst effects of climate change, and that failure to do so could risk global GDP being 20% lower than it otherwise might be.
On the other hand, if economic growth is sustained over the long term, future generations may be so wealthy that they will have nothing to fear. Lord Lawson claimed that people in a hundred years time would be "seven times as well off as we are today", therefore it is not reasonable to impose sacrifices on the "much poorer present generation".