North America is strides ahead of all other regions, including its nearest rival North and Western Europe, in producing high-quality science. Boasting a WFC of more than 20,000 in the Nature Index, its two constituent countries, Canada and the United States, have long enjoyed strong support for natural science, mostly from their research universities. But both are adapting to significant shifts in public funding in recent years. The United States, comfortably the global leader in the index, is weathering funding cuts that have curtailed many research agencies. Canada, which comes in seventh globally and has notable strengths in life sciences and earth and environmental sciences, is attempting to tie its research more tightly to commercial innovation.

The United States dwarfs its northern neighbour on nearly every measure, but the index reveals more nuanced information about how it uses its resources. For example, according to UNESCO, there are 1.25 million researchers employed in the United States, which is 3,979 per million citizens; Canada has only 157,000 researchers, but this translates to 4,563 per million people — a higher density. The Nature Index, however, shows that the United States is better able to leverage its researchers, producing a WFC of 14.9 per thousand researchers compared to Canada's 9.4 (see 'Researcher efficiency').

Researcher efficiency may be a factor in the relative lack of collaboration with countries outside the region, a metric that is lower than the global average across all subjects. The United States is relatively self-sufficient, particularly when it comes to papers in either Nature or Science (see 'Collaboration rate').

The region shows an above-average contribution to the life sciences, which accounts for nearly half of its output (see 'Research strengths'). For the United States, that focus has historically been encouraged by funding from the government's medical research agency, the National Institutes of Health (NIH) — whose budget, however, is shrinking — in real terms, it is now four-fifths of its value a decade ago (see 'National Institutes of Health'). Its Canadian counterpart, the Canadian Institutes of Health Research, also has seen its purchasing power wane in recent years.

United States: seeking stable growth

China, of course, is not the only nation ramping up R&D while we rest on our laurels.

The United States' WFC in the Nature Index is 18,643, more than triple that achieved by second-place and ascendant challenger China. But maintaining this supremacy might prove difficult: 2013 budgets for many US research agencies were flat. The prospect of prolonged federal funding constraints gravely worries many in the research community. “China, of course, is not the only nation ramping up R&D while we rest on our laurels, seemingly attached to the groundless belief that the US is so ahead of other nations that we can operate on cruise control,” observes Mary Woolley, president of advocacy group Research!America in Alexandria, Virginia.

The past decade has seen a drop in overall US research and development (R&D) funding of about 12% in real terms, say Matt Hourihan, director of the R&D Budget and Policy Program at the American Association for the Advancement of Science. Most of that budget decline hit defence-related R&D. “I think we will be treading water for at least a few years to come,” he adds. The Obama administration has proposed near-level funding of US$64.7 billion for basic and applied research in fiscal year 2015, and of US$68.0 billion for developmental research.

Life sciences are particularly strong in the United States. In 2013, the Nobel Prizes in Chemistry and in Physiology or Medicine both went to scientists based either wholly or partly in the United States. In the Nature Index, the country is also most dominant in the life sciences, where it accounts for just under half of the global WFC (See 'Life science share').

However, 2013 was a troubled year for US research, with federal sequester cuts in March, triggered by the failure of Congress to otherwise lower the budget deficit. These cuts hit science spending, for example slicing off about 5% of the NIH budget. Related turmoil effectively shut down most of the federal government in October, halting research at many labs. The NIH was forced to send 12,000 scientists home for “16 very, very long days,” says Lawrence Tabak, NIH principal deputy director. Uncertainty about a national commitment to science “casts a pall on young people who are considering a career in biomedical research”, he adds.

Overall spending has since crept up to around pre-sequester levels, but budget uncertainties continue. Another round of sequester cuts is scheduled for fiscal year 2016 unless federal deficit-reduction targets are met, says Hourihan.

Canada: getting down to business

Canada continues to punch above its weight in global science.

Life sciences are Harvard's strength Credit: MJBS/Thinkstock

Canada's WFC of 1,483 belies its relatively small population of 35 million (just 2 million more than Morocco), and the country “continues to punch above its weight in global science,” according to Paul Dufour, an independent science and technology policy consultant based in Gatineau, Quebec. Its strength is “largely a function of the enormous expenditures since the mid-1990s in higher-education research,” he says. Annual spending on natural science and engineering research by academic institutions has more than tripled in real terms, from Can$3 billion in 1996. (However, despite the long-term upwards trend, overall federal spending on science and technology from government, industry and academia has been heading south for several years.)

Canada spends about 1.9% of its gross domestic product (GDP) on R&D, a similar ratio to that of China and considerably less than that of the United States at 2.8%, according to estimates by Battelle Memorial Institute. R&D spending by industry and by national defence agencies, however, is much lower in Canada than in the other two countries.

Recently there has been a strong federal push to tie research more closely to business. One prominent example, Dufour notes, has been a retooling of the premiere lab, the National Research Council, to focus on business-led research. Also, “new funding going to universities has interesting clauses trying to target work closely to businesses,” Dufour says.

A number of federal initiatives have strengthened research efforts. Since 1997, the Canada Foundation for Innovation programme and its partners have poured more than Can$12 billion (about US$11 billion) into new buildings, facilities and other research infrastructure. Beginning in 2000, the Canada Research Chairs programme has created about 2,000 research professorships, with an annual budget of about $265 million.

Key areas of research such as quantum computing and neuroscience are supported by the related programme Canada Excellence Research Chairs, which allows Canadian universities to compete for leading international researchers. “Budgets and funding are limited, but the return on investment is worth it if Canada makes strategic investments in areas of global impact,” says Feridun Hamdullahpur, president and vice-chancellor of the University of Waterloo and chair of the U15 Group of Canadian Research Universities.

The Canada Excellence Research Chairs programme seeks to maintain the country's long-standing success in attracting researchers from abroad. According to a 2014 report from The Council of Canadian Academies, 51% of individuals holding science, technology, engineering, and mathematics degrees in Canada are immigrants. (That's about twice the percentage of foreign-born college-educated scientists and engineers working in the United States, according to National Science Foundation estimates.)

Three North American leaders

Three institutions exemplify the strengths of major North American academic organizations: the two US institutions that place highest in the Nature Index, Harvard University and Stanford University, and the top Canadian institution, the University of Toronto. The index reveals that these three have quite different research profiles.

Harvard has about 2,100 faculty members and its sponsored research funding totalled US$821 million in 2013. Stanford employs roughly the same number of faculty, with a sponsored research budget of $1.35 billion (including $452 million for the SLAC National Accelerator Laboratory, which Stanford operates on behalf of the Department of Energy).

The University of Toronto, with a faculty of about 12,500, is the largest research organization in Canada. The university and its partner hospitals received sponsored research funding of about Can$1.1 billion (US$1.0 billion) for 2013. As a public institution, it has about 67,000 undergraduate students, an order of magnitude more than Harvard or Stanford.

Posting a WFC of 852, Harvard comes in second among global research institutions, behind the gigantic Chinese Academy of Sciences with a WFC of 1,209. Stanford comes fifth with 553, and Toronto is 28th overall with 242.

Both Harvard and Toronto publish most in The Astrophysical Journal, with 403 papers from researchers at Harvard (representing 14% of all 2013 papers in this journal) and 91 from Toronto. There were also 89 papers from Stanford, although this Californian institution published most frequently in the interdisciplinary journal Proceedings of the National Academy of Sciences (PNAS) (see 'Top ten journals'). Nevertheless, the institution with the strongest slant towards physics overall is Stanford, with 39% of its output in this field. (see 'Institutional subject spread')

Stanford's five top journals in the Nature Index are all in the physical sciences. The university hosts the SLAC Lab, which on its own achieved a WFC of 56. Among SLAC's accomplishments was a Nature paper that a made a significant step toward creating an electron accelerator on a chip. However, it is the Massachusetts Institute of Technology (MIT) that published more physical sciences papers than any other North American institute, with a WFC of 228 – that's more than Stanford's 215 and Harvard's 195 (see physical science table, page S107).

Earth and environmental sciences makes up only a small proportion of the total Nature Index papers, and all three institutions publish fewer than the global average in this field. The top North American institutions are two government agencies: NOAA and NASA (see Earth and environmental sciences table, page S105). Stanford is fifteenth globally, but is in the process of expanding its Earth Sciences department — and in 2013 two of its faculty were given prestigious MacArthur Fellowship (“genius”) awards.

One of Stanford's high-profile papers in this field was published in Science, and found that current climate change is happening an order of magnitude faster than at any other time in the past 65 million years.

All three institutions published most of their papers in the life sciences, particularly Harvard where this subject accounted for more than two-thirds of its output. Indeed, Harvard is the leading institution in the Nature Index for life sciences (see life sciences table, page S104); this is the only subject where the Chinese Academy of Sciences is not top.

This achievement partly reflects the sheer size of Harvard Medical School, which has more than 10,000 academic appointments in affiliated teaching hospitals alone, compared to around 700 for Toronto and 600 for Stanford. Harvard's interdisciplinary groups, such as the Harvard Stem Cell Initiative and Wyss Institute for Biologically Inspired Engineering, also did well in Nature and Science.

It is in the Nature and Science count that Harvard really shows its strength.

It is in this count where Harvard really shows its strength. In 2013 Harvard contributed to 199 papers in total in Nature and Science, (see 'Nature and Science output') accounting for 9% of the total Nature Index articles it contributed to, making it by far the global leader by this metric. In fact there are three US institutions in the top three Nature and Science list by WFC: Harvard is followed by MIT and then Stanford (see Nature and Science table, page S108). The University of Toronto published 34 papers in Science or Nature, representing 6% of its output in the index. All three North American universities are comfortably above the world average of just over 3%. (See 'State analysis'.)

In terms of online attention (everything from Twitter to news articles) for scholarly papers, Altmetrics provides some interesting data. In this respect, Harvard has a higher visibility than the other two institutes. One of its papers from Science, “Poverty impedes cognitive function” (see 'Harvard's online visibility'), is in the top five papers of the year according to altmetric.com (as of 22 September 2014). However, it is a Stanford Nature paper, “Structural and molecular interrogation of intact biological systems”, about a way to make biological tissue transparent, that gained the highest score for papers from a single institution.